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FAQs on Mastacembelid, Spiny Eel Systems

Related Articles: Spiny EelsThe truth about spiny eels; A closer look at these popular but problematic oddballs by Neale Monks, Husbandry of the Barred Spiny Eel, Macrognathus panacalus by Marco Lichtenberger, 

Related FAQs: Spiny Eels, Spiny Eel Identification, Spiny Eel Behavior, Spiny Eel Compatibility, Spiny Eel Selection, Spiny Eel Feeding, Spiny Eel Disease, Spiny Eel Reproduction,
By Species: Fire Eels, Peacock Eels, Tire Track Eels,

Thank you and a Question. Spiny eel sys., gen.      5/1/18
I just wanted to say thank you for setting up Wet Web Media and the education and information you provide. It means so much to me as it has saved me from a lot of headache and heartache.
<Glad to hear it!>
Yesterday I asked Neale about Anableps because I love the fish and was looking for something for an open 55 gallon tank. The information Neale provided helped me understand the Anableps were not a good choice for me
and a 55 gallon was not a good tank for this species.
<Possibly not.>
So I've been browsing your web site for ideas and came across some posts and an article about Spiny Eels.
<Nice fish. Interesting to watch, but tricky to keep, and finicky feeders.
Somewhat prone to skin infections.>
I love Eels, but most of them get so big that I'm not sure they're a good idea, especially for a 55 gallon tank.
<Can be a problem, yes. There are some small species of course, so there's "something for everyone" in the family Mastacembelidae. Just not really recommended for beginners who don't understand their specific needs, i.e.,
sand (not gravel) substrate; predominantly live or frozen foods, not dried food or flakes; tendency to escape through aquarium hoods; and so on.>
I have a Peacock Eel that lives with my BGK in a 125 gallon and is a very beautiful fish. But the posts I was reading spoke of Macrognathus Pancalus and Macrognathus Circumcinctus and I was happy to read they get along with each other.
<They/these smaller Spiny Eels do get along for the most part, yes; but this does vary with species. As a broad rule, Macrognathus species are fairly tolerant if given enough space, whereas Mastacembelus species tend to be more territorial.>
But then I read something that really struck me and helped me make my decision about my open tank. It said that ALL Spiny Eels benefit from a little salt in the water.
<Sort of. While they aren't brackish water fish, salt used therapeutically can help them a lot. As you've read, we're talking small amounts of salt, as if you were treating for Whitespot. There are one or two species that do occur in low-end brackish conditions of course, including Macrognathus pancalus and perhaps Macrognathus aculeatus as well. So these might be kept in systems alongside things like Knight Gobies and Mollies that appreciate a little salt.>
I immediately thought of my poor Peacock Eel, living in pure freshwater with my BGK and Rope Fish.
<He's probably fine, in all fairness. Black Ghost Knifefish are very much "miner's canaries" when it comes to environmental conditions, and if both fish have been doing well for some time, years perhaps, they're probably in
good shape thanks to your good care of them.>
I can't add salt to the BGK's water, so I decided to move my Peacock Eel to the open 55 gallon and add a little salt (as you indicated, 2 grams per liter - I use Instant Ocean because it's all that's available in my area) and make that tank my "Eel" tank.
<Sure. But acclimate the fish carefully, and check for any signs of negative reaction, such as frenetic swimming or heavy breathing. "Change for change's sake" is something politicians are big fans of, but when it comes to keeping animals, it's not always a good idea. Animals can become used to conditions that might not be optimal, and even if you're improving their world, sudden changes can stress them.>
But it is my understanding that Peacock Eels will not tolerate each other except in very large tanks, so here's my question; my local fish store has other eels for sale that are of the Macrognathus genus (though they are not identified as either Pancalus or Circumcinctus) and they tell me the will be around 8 - 10 inches as adults. As indicated, either of these species will get along with their own kind, but will they get along with my Peacock Eel?
<In a biggish sort of tank with plenty of hiding places they should be fine -- and I'd introduce them all at the same time if at all practical, so that territorial boundaries aren't already established.>
Or, if they won't, would my Peacock Eel do well with my Violet Goby and Sailfin Mollies (SG 1.005)?
<I would not mix them with these fish; even the salt-tolerant Spiny Eels aren't really true brackish water fish (so far as I know) and anything above SG 1.002-1.003 is probably going to stress them. Cheers, Neale.>
Re: Thank you and a Question      5/2/18

Ok, that makes sense.
<Good oh!>
When I got my Peacock Eel (I got both him and the BGK a little over a year ago), he had only one "spot" but now he has three. When I get a chance to see him (more of him than just his head poking out from the sand - but always when I do the weekly water change) his skin is even colored with no
blemishes. The BGK is now 7 inches long and though mostly nocturnal, he comes out in the daytime frequently enough for me to see that he also looks physically as he should - no tears in the fin or any blemishes in the skin. Both fish have good weight. So if I'm understanding you correctly, the fact that they seem to be doing well is the indicator to "leave well enough alone."
<That would tend to be my approach, at least.>
As for the new eels, my aquarium store friends told me the supplier lists them as Macrognathus Pancalus. They currently have three of them and they've had them for over a month. While they are small, the seem to be doing well. They're inexpensive, and I'm thinking of getting all three and see if they'll get along at least enough so that they're not hurting each other.
<Should do.>
This tank has a lot of hiding spaces, made from PVC gutters, and they would be the only fish in the tank except for the Bristlenose cleaner.
<No problems combining this with Spiny Eels.>
This tank also has the old, really heavy, glass lids and a canister filter with quilt batting stuck in around the intake and outflow tubes so there's no way they can get into the filter or out of the tank. What do you think?
<Definitely worth a shot! Cheers, Neale.>
Re: Thank you and a Question      5/2/18

Thank you!
<Most welcome. Neale.>

Spiny eel      2/12/16
Hi I just got a spiny eel and was wondering if I could please get a detailed list of what substrate, chemical balance and so on I need to properly take care of it. Also need a list of fish I can keep with my eel so I can fill the tank soon. I'm only finding info in bits and pieces throughout your website. Thank you
<Ah yes; what we know re Mastacembelids is posted here:
and the linked files above. Bob Fenner>
Re: Spiny eel... Not a reader       2/13/16

Okay...also, is it better just in general to use sand substrate vs. Rocks at the base?
<Soft sand, as gone over on the site>

Zig Zag eel, sys., ID  3/29/13
Hi there my name is Anthony I purchased a zig zag eel about three months ago and I was on a bit of a budget when I bought him or her. The eel is currently housed in a 25 gallon tank with a Pleco, the substrate is a small gravel since the store I bought it from was not very knowledgeable on the species as the eel was sold to me as a "fire eel". I am upgrading the tank to a 55 gallon early next week and would like to use sand as the substrate but can't find a clear answer on what sand to use. I was also wondering what exact species of the spinet eel I have, the eel does not have the wavy tire track pattern but it does not have a zig zag pattern either. It's more of a bunch of thick stripes on an angle that run from top to belly, mind you there are a couple of thinner lines that run onto his belly. The back fin is fully connected around his tail so there is no separation in the tail fin, I am hoping I have one of the bigger species of the spiny eel but it's not a big deal if its not. Thank you for your help in advance.
<In the US at least, the common "Zigzag Eel" of the trade is what used to be called Mastacembelus armatus, but may well be Mastacembelus favus or indeed some other closely related species. All are light brown with dark brown markings, but there's a good deal of variation in the exact shape of the markings. Use Google images or some other search engine to look for photos. Do also look at Macrognathus circumcinctus while you're at it; while it isn't normally traded as the Zigzag Eel, it's just possible it might be. Otherwise, send us a photo, and maybe we can help you identify your fish. Cheers, Neale.>
Re: Zig Zag eel 3/29/13
I just quickly did a Google search on the Macrognathus circumcinctus and many of the pictures look very similar, thank you for the help.
Now this brings a another question what is the estimated full grown size of this species?
<Not that big, around 15-20 cm seems typical. Basically a community tank fish, though very small species such as Neons may be eaten, so choose tankmates too large to be swallowed.>
I had mentioned in my other message that I would like to put a sand substrate in my new tank but was unsure what sand was best for the spiny eel. I have read mixed reviews of live sand in a freshwater tank and have read playground sand and pool filter sand work as well, I just want to use the best as I would like to have the best conditions for my spiny eel.
<Smooth silica sand (which is lime-free, so won't alter pH) is ideal. In the UK this is widely sold in garden centres for use in horticulture, and I'm led to believe the same stuff is also sold as poll filter sand. Avoid anything sharp or not lime-free, as both these will be unhelpful, to say the least! Silica sand seems very bright at first, but after a few months it ages nicely, as algae and bacteria coat the grains, so don't worry too much about the colour. If you want though, you can stir in some fine pea gravel to darken it a bit, and your Spiny Eel won't mind. Cheers, Neale.>
Picture of my spiny eel 3/29/13

This is a picture of my spiny eel looks a lot like the Macrognathus circumcinctus or half banded eel
<Indeed, does look like Macrognathus circumcinctus, or something very closely related. All Macrognathus species are pretty similar in care; do read Marco's excellent piece on M. pancalus, here:
Cheers, Neale.>

Fire eel  - 01/12/2013
<Hi, Michele!  Sabrina with you today.>
I have a 29 gal 30"long tank with two Glo Fish and one Gourami. 
<The Glo-Fish, actually a genetically modified zebra Danio, are schooling fish and would really like to have more Glo-Fish buddies.>
Three weeks ago I added a fire eel. 
<Oh....  A very interesting animal, but they get a bit too big for a 29g tank....>
The store knew I had a 29 gal tank and gravel bottom but sold it to me. 
About one week after having the eel I decided to read up on them
<Please learn from this experience - the next time you find a potential new fishy pal, no matter how awesome, take some time to read up on them prior to purchasing them.  It may save you some heartache.>
only to find that I should not have a gravel bottom and that my tank size seems to be too small. 
<Yes.  This fish really needs a soft, fine substrate....  and will outgrow this tank.  Worse, when they find themselves in spaces that they don't like, they decide to exit the aquarium and turn into fish jerky on the floor.  It is VERY hard to keep them inside an aquarium, so make certain you have NO holes in the lid, anywhere, and that the lid cannot be pushed open easily from the inside.>
Now I need to make a decision on whether I should be keeping this eel in this size tank. 
<I, personally, wouldn't, unless the animal is still quite small and you can/will upgrade tank size.  The gravel substrate is the biggest hurdle, though.>
I have called the store I bought him from and they seem to feel the tank is fine and say that the fish will adapt to the small tank. 
<I think it's fair to say that I disagree with this.  Vehemently.  No fish will "adapt" to a tank which is too small.  Will it survive?  Maybe.  But is it fair?  Reasonable?  Conscientious?  In my opinion, definitely not. 
Once again, if the animal is still small, and you can/will upgrade tank size, then I think you're okay - for a time.  But not when it gets big. 
And it WILL get big.  Longer even than your current tank.  Your tank is 30 inches long, right?  Mastacembelus erythrotaenia gets about 40 inches long.
 Envision what size space an animal 40 inches long will find appropriate. 
I've seen some videos on YouTube of very large fire eels....  They are very, very large....  It might be worth your while to look these fish up on YouTube and see some of these videos yourself, to understand truly what your animal is and will become.>
My question to you is this inhumane to keep him, I am very strongly thinking on giving him back to the store.
<I, personally, feel that it would be "wrong" to keep a fire eel in a 29g tank, except as a very temporary home while it is a baby.>
I also know that if I decide to keep him that I would have to change the gravel to sand and from what I hear that can cause some problems with the tank with the cycling and I risk the fish getting ick. 
<You won't risk the fish getting ick, Ichthyophthirius multifiliis, by changing your substrate.  This is a parasite that has to come from a fish introduction.  Although you might experience interruption in the cycle, you can combat this with frequent water changes, or by only changing out one half of the substrate, waiting a few weeks, and changing the other half.>
Also I bought two Pictus Catfish from this same store and put them in a 10 gal tank by themselves but they seem to be bouncing off the walls.  Again is this tank not the right size for them?
<Very correct.  This active catfish needs a larger space than 10 gallons. 
It might be worthwhile to see if there are other, more conscientious shops near you that might be a little more thoughtful about the lives of the fish that they're selling.  But regardless, next time you find a fish you want, please read up on them first.>
Thank you very much for your time.  This means a lot to my son and I.
<Thank you for your kind words, and for sharing the world of fish with your son.  He is sure to learn much about the world around him!>
<Best wishes to you and your fish (and your son!),  -Sabrina>

spiny eel, sys.   3/4/12
After a lot of research (your website helped a lot ) I decided to get a spiny peacock eel . I have prepared my tank for one, but I have a piece of sandstone that is very sharp would this harm the eel? it also is on sand .
if the eel dug under the rock could it fall and crush him?
Thanks, Aaron
<Yes, remove the sharp rocks. Not worth the risk. If you can, add a small amount of salt, 1-2 g/litre, and you'll find this species considerably more disease-resistant. Cheers, Neale.>

Spiny eel set up   9/24/11
Hello there,
I'm from New Zealand and looking at adding a spiny eel of some sort to my current set up 29gal - 80cm long, 30cm wide, 45cm high. Will this be an acceptable size for one of the small Spiny eels?
Looking at a Peacock Spiny eel, or a Half Banded Spiny eel.
<Both good species; ideally kept in very slightly brackish water, 1-2 grammes/litre making all the difference to their long-term health.>
Also getting mixed information about how they go with small fish, have Corys (3cm) and rummy nose tetras are these likely to become food?
<The Corydoras won't be eaten, but will compete for food, so I wouldn't recommend them. Or, at minimum, I'd get the Spiny Eels first, keep them a couple of months, and make sure they're settled in and feeding well. Newly imported Spiny Eels are slow, shy feeders and Corydoras will steal the wet-frozen and live foods the Eels need. The tetras, if too large to be eaten, will get along fine, but I wouldn't keep them if you choose to add salt. If you do that, a robust species known to be tolerant of slightly brackish water would be better -- Guppies, Limia spp., Dwarf Rainbowfish, X-Ray Tetras, etc.>
The tank has silica sand and is well planted.
<Floating plants are almost essential. Without them, you won't see much of your Spiny Eels, and their tendency for suicidal leaps will be magnified.>
Appreciate your advice
Cheers, Michael
<Do read:
Cheers, Neale.>

new Fire eel , Neale's go  10/25/10
Hey guys, I just got in a new 7inch fire eel and it looks ok, but I noticed that while it was in the fish store they had it in gravel and any time I would go look at it b 4 taking it home it would be buried in their regular size round gravel. In my tank I've got white and back sand, and sum plants and stuff for him to hide and feel more comfortable. my question is, is there a reason he is not burying himself in the sand but keep chilling at the top of the water in the plants? I've read that ppl talk about this but they say their eel is on its side or upside down. mine is not its just up there not really doing n e thing. don't get me wrong at night he moves around and stuff. but .. how come no burrowing?!? it that ok or what?
thanks for the help guys at WWM :)
Bless! Brad
<Hello Brad. If you have plants at the top of the tank, especially floating plants, it is very normal for Spiny Eels to tangle themselves up in those plants. In fact spawning seems to take place in floating plants. So if your chap otherwise looks healthy, and better yet, is eating, I wouldn't worry about it. Cheers, Neale.>
new Fire eel, BobF's turn  10/25/10
Hey guys, I just got in a new 7inch fire eel and it looks ok, but I noticed that while it was in the fish store they had it in gravel and any time I would go look at it b 4
<Please, no "net speak">
taking it home it would be buried in their regular size round gravel.
<... please read here:
and the linked files above re Mastacembelids>
A/the choice of substrates with spiny eels is crucially important>
In my tank I've got white and back sand, and sum plants and stuff for him to hide and feel more comfortable. my question is, is there a reason he is not burying himself in the sand but keep chilling at the top of the water in the plants?
<Likely this gravel is too coarse, sharp... painful to its skin>
I've read that ppl talk about this but they say their eel is on its side or upside down. mine is not its just up there not really doing n e thing. don't get me wrong at night he moves around and stuff. but .. how come no
burrowing?!? it that ok or what? thanks for the help guys at WWM :)
Bless! ..Brad
<Brad, in future, please run your missals through a spelling/grammar checking ahead of sending.
Bob Fenner>
Re: Sick Eel with White Patches

Thanks, unfortunately the eel did not recover and had to be removed.
<Sorry to hear this.>
This was an extremely fast-moving infection, especially for such a large fish (3'). From zero symptoms to dead in 3-4 days.
<Indeed, very fast.>
Nitrates were tested at 30 or less (per color scale) every month or so, but it is a 400 gallon tank with only 3 fish and 2 (now 1) eels so the biological load is light. Has about 250 lbs of live rock in the main tank and a bioball filtration system in the sump. Water changes 40 gallons every 10 days. I don't have a PH score right now but most likely it is fine given this maintenance.
<Yes, sounds OK.>
Both eels came from LFS about 6 months ago that was trying to get rid of them due to lack of demand. Neither one can be described as aggressive eaters in the sense they will dash out and grab at food, have to put the food on a stick and put it near their mouth before another fish grabs it. So they got plenty food but maybe not the strongest to start. Maybe that is why the LFS was getting rid of them. I will watch the remaining one and continue to monitor tank conditions and consider the hospital tank at the first sign of trouble.
<I'd also add vitamins to its food regularly (at least once a week) to replace anything lost due to freezing and thawing processes. Cheers, Marco.>

Fire eel question (Bob, some questions about your Spiny Eel piece)<<Ok>>    10/19/10
Hey Guys,
I was at my LFS and came across some amazing Fire Eels.
<Beautiful fish, though very difficult to keep for a variety of reasons.>
A fish that I had only ever seen in videos on YouTube. I knew right then that I wanted to bring one of them home with me. I've got a 8'x2'x2' tank, crushed coral substrate and smooth black river rocks making caves with 6, 5" Fronts, 2 4" blue dolphins, 1 9" black Arowana and 2 4" Altolamprologus.
<Here's the deal. Hard water isn't a major problem as such, but crushed coral will probably raise the hardness and pH well above the comfort zone for these essentially soft water fish. They really need something in the range 5-20 degrees dH, pH 6-8. Yes, there are spiny eels in both Lakes Malawi and Tanganyika, but not Fire Eels! Any of the Malawian or Tanganyikan species would get along fine with all of these fish, except the Arowana, who has no business being in a hard water community at all, and in
any case, will soon start seeing the smaller fish as food.>
<<And crushed coral is a very poor/unsuitable substrate for keeping Mastacembelids>>
In the research that I've been doing over the weekend I think the Fire Eel would do ok in my tank with the fish I have now.
<Not quite. The tank is big enough, and Fire Eels have certainly been kept with Arowanas, particularly the relatively peaceful South American Arowanas. On the other hand, the water chemistry required by Malawian and Tanganyikan cichlids is far towards the hard/alkaline end of what Arowanas and Southeast Asian spiny eels appreciate. In short, not a textbook combination of species.>
Question 1) will it?
<Does depend on water chemistry, about which you've said nothing. Also, the substrate needs to completely smooth, I'd recommend smooth silica sand, or failing that, very fine, rounded gravel. Crushed coral and/or coral sand is right out. Any rocks need to be smoother than smooth, baby's bottom smooth.
Anything with any sharp or even rough edges is putting your Fire Eel at severe risk of death. The danger is, as I hope you understand, damage to the skin. Once scratched, these fish are astonishingly prone to bacterial infections. They react badly to copper and formalin, and even antibiotics have a poor track record when it comes to treating sick fish. Obviously, this predisposition to disease is another reason why "feeder fish" should never be used, and diet has to be very carefully controlled to include lots of thiaminase-rich foodstuffs. Earthworms are the single best food around for spiny eels.>
the eels at the store are about 6" to 7".
I have a cover on the tank now but are they really that adapt at escaping?
<Yes. If they can escape, they will. DO NOT delude yourself otherwise!>
Those are the basic questions I have, my main concern would be the small white blob spot on the tail of one of the eels. From what I've read it could be Ick, as the eels had just got to the shop a day before, and if so adding salt and increasing the temp in the tank would help kill the bacteria?
<Salt/heat will treat Whitespot just fine. As for bacteria, there is some argument, e.g., in Baensch vol. 1, that maintaining slightly brackish conditions improves the health of Fire Eels and indeed Spiny Eels
generally. I kept my Tyre-Track Eel in brackish water for several years alongside mollies, Rainbowfish and other salt-tolerant tankmates. Baensch recommends 1-2 teaspoons per 2.5 US gallons, or about 6-12 grammes per 10 litres. This is a very low dosage, far below what is officially brackish water and not enough to stress freshwater fish in most cases, but do observe your other fish and see how they react.>
However in one of the articles I found on your site,
Bob Fenner said "Should any of the spiny eels in the system exhibit red areas, particularly near fin origins, or white, blotchy markings, leave all of them. They are likely to be soon dead."
<Bob is on the money here. Fire Eels and spiny eels generally are extremely prone to these bacterial infections, and if the retailer has done stupid things like keeping them in tanks with gravel, or has fed them feeder fish, then all bets are off. You might take a gamble on a healthy specimen alongside one or more sickly ones, but for the best chance, pick a healthy fish from a batch of healthy fish.>
What is this 'white blotchy marking' on the tail?
<It's essentially Finrot, some sort of Pseudomonas or Aeromonas infection of the skin. You're looking for patches of white mucous initially, followed by reddening, dead white skin, cloudiness of the eyes, and then death as the disease progresses.>
is it really that bad,
is there nothing I can do about it
<Antibiotics may help with minor infections, and maintenance in slightly salted water is probably a plus. But once a spiny eel gets really sick, they are notoriously difficult to treat.>
so I can bring one home and nurse it back to health, or should I just stick to admiring these fish on YouTube Videos? Thanks for your help guys! :)
<Do be sure to read everything you can about these fish, and act accordingly. Both Marco L. and myself have kept these fish and written articles about their needs:
The bigger species of Mastacembelus are perhaps less sensitive to substrate type than the smaller Macrognathus, but apart from the rock-dwelling Malawian and Tanganyikan species, all spiny eels should be kept in environments as free from sharp edges and rough surfaces as possible.>
Bless! Brad
<Cheers, Neale.>

fire eel. Mastacembelid sys., hlth.  6/10/2010
Hello, I found your site doing a search on fire eels.
<A lovely fish.>
I bought one a few weeks ago and I put him in my tank with gravel. I noticed he was digging so I took all of the gravel out of the tank and made my tank suitable for fire eels. I now see white scrapes on his body with a couple of white spots.
<Yes, this is the classic problem. Smooth, round gravel is just about okay if their are lots of bogwood roots and caves where the Fire Eel can hide.
But if he feels the least vulnerable, he will try to dig, and when they dig, they get scratched.>
He is eating fine and is quite happy.
I am concerned about the white scrapes/spots. Do I need to medicate or will the scrapes/spots go away?
<I wouldn't medicate directly, but a small amount of aquarium salt can help. Baensch recommends 1-2 teaspoons per 2.5 gallons, which isn't very much. For whatever reason, small amounts of salt seem to minimise the risk
of secondary infections where spiny eels are concerned. Note that they aren't brackish water fish, so marine salt isn't what you want here; marine salt mix would raise the pH and hardness, not just the salinity. Just plain vanilla aquarium/tonic salt, sodium chloride.>
I have done so much research and don't know if I should medicate. The spots have been on my eel for about 3 days. Your help would be much appreciated!
Best Regards, Jennifer
<A cheap, easy fix here Jennifer, so be of good cheer! In clean, clear water he should heal just fine. Don't forget to keep him nice and warm though; these eels are hothouse flowers, and need to be kept around 25-28 C/77-82 F. If they're chilled, their immune systems will weaken. Cheers, Neale.>
re: fire eel 6/11/2010

Thanks Neale for the quick reply!
<No problem.>
The tank is at the right temperature and I did add some aquarium salt this morning.
I will keep a good eye on him and if I see things worsen, what kind of medication would be best for my newest family member?
<As stated, salt is the best tool for prevention as well as treating things like Ick. Otherwise antibiotics, possibly Methylene blue. Avoid copper, formalin and malachite green.>
He is an awesome fish and we have become quite attached to him.
<Indeed he is.>
I will do what ever it takes not to lose this guy.
<Quite right!>
Thanks Again! Jennifer
<Cheers, Neale.>

Tire track eel (sys., fdg. reading), Trichogaster microlepis questions 01/30/10
Hello, I've recently purchased a Tire track eel (Mastacembelus armatus) and a very large (quite beautiful) Moonlight Gourami (Trichogaster microlepis) from my LFS, and added them to my main tank, which currently has six small silver dollars, a Black ghost knife, a Leopard Ctenopoma, a large Rhino Pleco and two Botia Kubotai inhabiting it. After adding them, they all seem to be getting along very well, the Botias chasing the eel a few times, but nothing more than that. Since the Gourami is the only inhabitant of the upper regions of my tank, it's not being bothered by anyone. The eel is wonderful, swimming around the tank, looking though thru glass at us, and so on. The only problem is, he likes to play in the filter. He swims up into the filters
<? The intake/s and discharge are not screened?>
that hook on to the back of the tank, stays there for a while, and then slowly swims out when he decides to. Now, since he doesn't seem to be getting hurt, I don't mind-- I'm just worried that he might think he's going
into the filter, but really be going over the back of the tank. I'm trying to find something to cover the back of it, but until then, he's at risk of climbing out
<A very common issue/problem with captive Mastacembelids>
(I should have eel-proofed my tank before I got him).
<Yes. Cover all openings now>
What I'm actually asking though, is what diet is best for them-- Would a diet of frozen bloodworms, flake, shrimp pellets, and occasionally live brine shrimp/guppy fry suffice?
<Read here: http://wetwebmedia.com/FWSubWebIndex/spinyeelfdgfaqs.htm>
I know they can be timid while feeding around more aggressive fish, so I I'll be using the turkey baster. Also,
will the Gourami get along with a Butterfly fish?
<Maybe... depends mainly on the size of the system>
The surface area of my tank is quite large, with ample floating plants, and the Gourami doesn't usually stay at the very top of the tank where the Butterfly fish would be (would have got the butterfly instead, but my reserved specimen at my LFS had a fungal infection yesterday, waiting for a new shipment...). Thanks! -Jack
<Welcome. Bob Fenner>

Substrate for Peacock Eel 3-5-09 Hello All!! I have searched high and low for the answer to this question to no avail. Is Estes' Ultra Reef sand OK for my spiny Eels, Flotsam and Jetsam? <Not familiar with the brand, but seems to be a lime-free (i.e., no calcium carbonate) sand. Should be fine. Feel some: if it feels sharp, no, it isn't safe; if it feels silky smooth, then it's fine.> Before I acquired my eels, I had a natural gravel in my tank that was obviously not appropriate so I bought the Ultra Reef sand, removed the gravel and put in the sand, thinking that sand is sand is sand. <No, not really...> Now I am reading that a silica-based play sand is best. <Play pit sand and swimming pool filter sand both seem popular in the US, while here in the UK we tend to go for the smooth silver sand used in gardening. But use whichever suits. The two key things are [a] it's lime free; and [b] smooth in texture, as opposed to "sharp", which means something specific in the context of sand.> I really don't want to stress my eels any more than necessary so I would prefer to leave the sand that is in there now alone, but if there is a chance my babies will be hurt I will remove the sand immediately. <Feel it. If it feels nice and silky, you're fine.> What do you think? Lana <Good luck, Neale.>

Striped peacock eel 09/04/08 Hey, <Hello.> My name is Brodie, I just purchased a striped peacock eel from my local fish store. My water in my 20 gallon long tank is sitting at about 78-79 degrees, and it has a rock cave, some plants, and a piece of drift wood. So from my research the tank has plenty of the dark hiding spaces striped peacock eels prefer. <Okay. What about the substrate? Spiny eels need sand or small rounded gravel. In addition it would be good if the rocks had no sharp edges.> After I acclimated him to the water he immediately dove down into the rocks, which I read would happen if the tank is too cold, <no> but it's at the recommended temperature. Also he looks to be a little under nourished, I think the store was feeding them fish flakes. I read I can force feed him blood worms through an eye dropper, and this will replenish his health into a sociable tank mate. <I would not do that too much stress.> In the tank as well are 5 tiger barbs which I read do fairly well with the striped peacock eel. <This tank will be overstocked in my opinion once your fish are grown.> I would like to know if you think him burring himself in the rocks right away is a reaction to being in a new tank, <Yes.> the other fish, or because he isn't healthy from the pet store? Also I would like to know if the force feeding is a good idea? If not, what might I try to get the little guy up and running like he is supposed to act? <As food try feeding at night when the barbs are asleep and the eel feels more safe. In the beginning they are almost always nocturnal, which can change with time and patience. Bloodworms and live earthworms (nightcrawlers) of adequate from a toxin free garden would be a good choice of food items to start with. The small earthworms can be fed with tweezers, just dont stress the animal too much. Please read http://www.wetwebmedia.com/FWsubwebindex/matacembelids.htm (including the linked FAQs on top of this page) and http://www.wetwebmedia.com/FWsubwebindex/spinyeelsmonk.htm and http://www.wetwebmedia.com/ca/volume_4/V4I3/Spiny_Eels/Spiny%20Eels.htm.> Thanks for your help. <Welcome. Marco.>

Re: Striped Peacock Eel   9/6/08 Thanks for the information. <Welcome.> I have the small round gravel in the tank, and the eel went right after the blood worm I cut for him. <Glad to hear. I guess the feeding issue is solved.> I have an old 29 gallon tank I can set up for the eel or the tiger barbs when overcrowding due to the growth of the fish occurs. <Very good. Have fun with your new pet. Marco.>

Twitching Eel? 1/9/08 Hi guys! <Ave!> I own 2 Macrognathus siamensis (Peacock Eels) and I recently moved them to a 20gal tank. One of them keeps on twitching, any ideas why? <Quick question: gravel or sand? Spiny eels in tanks with gravel are notoriously sensitive to bacterial infections. So while this might be nothing more serious than Ick, it might also be the start of something more critical. The lifespan of Spiny eels in gravel tanks is distressingly short because of this often ignored issue. Replace gravel with soft sand (silica sand is ideal).> I'm hoping to get an e-mail back soon. <You can certainly hope.> Thanks! a concerned friend. <Cheers, Neale.>

Fire eel and gravel   1/3/08 Hi (Neale, Bob, whoever?) - <In this instance, a very jet-lagged Neale.> I have a 6 inch fire eel with a 2-3 inch thin bar Datnoides and a 2-3 inch kissing Gourami in a 30 gallon tank. The fire eel and Datnoides will soon be moved to a 135 that is cycling as we speak and eventually to a 300 gallon tank with a clown knife so no worries about tank size (I hope...). In any case, the gravel I have in that tank is relatively large, smooth edged gravel (each piece is about 1/2 inch long and rounded). I also have a fake log / cave thing and a little ceramic house in the tank as well in addition to a few fake plants. In any case, my question is will the fire eel hurt itself burrowing into the gravel that I have? If so should I move all the gravel out of the tank? Finally, would a fire eel, Datnoides, clown knife and silver / black Arowana be ok for a 300 gallon tank? <I am 100% against keeping Spiny Eels in tanks with gravel. I have seen too many of these lovely fish get scratched by the gravel and then acquire some sort of difficult to treat bacterial infection. The size of the eel likely makes a difference, but at a mere 6", I'd not take the chance. Adult eels (say, over 18") seem to be less fussed, perhaps because they dig less anyway and will happily make use of artificial caves and burrows. But small eels are too easily damaged. I simply can't recommend any small or juvenile Spiny Eel be kept in a tank without some sort of fine sand. Silica sand is ideal. You will also get to see your Spiny Eel burrow and hunt for food in a more natural way, surely a better way to keep it?> Thanks, Raymond <Don't forget floating plants: Spiny Eels are apt to jump out of tanks without floating plants. That old standby, Ceratopteris, is ideal. With a dense "canopy" of floating plants, your Eel will spend a lot of time tangled among the roots where it will much easier to observe than otherwise. Cheers, Neale.>

Re: Fire eel and gravel  1/5/08 Hi - So should I take out all of my gravel and replace it with silica sand? And if I do that will that negatively impact the nitrogen cycle that I have established in there already? Thanks, Ray <Greetings. Assuming you don't have an undergravel filter, then removing the gravel and replacing it with sand will have ZERO effect on the nitrogen cycle. In a tank with canister filters, virtually all the biological filtration will be happening there, and not in the gravel. Cheers, Neale.>

Advice on spiny eel, sys. mostly   7/29/07 Hi there! <Hello!> I have a five gallon tank with a peacock spiny eel (about six inches long) that I have had for about four months now. I replaced the gravel that I used to have in the aquarium with sand about a month after I got him, and since then he hasn't come out at night. <Normal. They're nocturnal and very shy, especially when kept alone. I'm assuming you have Macrognathus siamensis, the most common species. A small, pinkish brown species with a series of eye spots on the dorsal fin.> He used to come out every night and swim around a little, but since I put the sand in, he stays mostly buried all the time. every few days his head is in a different place, so I know he is moving around. <Yup. That's what they do. Eventually, they become more outgoing, even trainable. But a happy spiny eel is a hidden spiny eel.> But a couple weeks ago I got a snail and an Oto fish to help with the algae that was accumulating in the tank, and since then he hasn't moved much at all, and keeps all but his nose buried most of the time. is he happy? do you think the fish scares him? <No. But Otocinclus catfish are *schooling* animals and pine away when kept singly. They're also short lived unless you have *excellent* water quality.> also, since he has stayed alive all this time I assume that he is eating, although I have never witnessed it, nor have any evidence of it. I keep a good number of live blackworms in the tank, and the number seems to dwindle, but I'm not sure if he really is eating them or if I am just sucking up allot of them when I vacuum the sand or do water changes. <Spiny eels enjoy worms of all types, from Tubifex and earthworms through to mealworms and bloodworms. The main thing is that there is nothing competing with them at nighttime. No loaches and no catfish (your algae-eating Otocinclus are an exception). Frozen bloodworms are the easiest staple. Assuming that there's nothing else to steal his food, your spiny eel will scarf up any bloodworms he finds at night. You could dump a pile of them in the corner one night and see what's left in the morning. But really, I wouldn't worry too much if he's healthy after 4 months.> could he have stayed alive this long without eating? <No.> is there any way to know if he is actually eating the worms? <Not really. But if he looks nice and plump when you see him swimming about, then he's eating them.> thanks so much for all of your help! Tori <Hope this helps, Neale>

New peacock spiny eel, sys., fdg.    6/2/07 Hi! thanks for all your advice > I got the eel, he's about six inches long and looks well fed. no white blotches on his skin or signs or irritation. <Very good.> > he is hiding under the gravel in my tank right now, but there is a cave in there that I hope he will move into when he feels more comfortable. <Please replace the gravel with sand as soon as possible. In my experience, small spiny eels die when kept in tanks with gravel. The problem is that they try to dig into the gravel, scratch their skins, and get infected with various bacteria. Once sick, they are impossible to treat. I have seen this happen so often that keeping small spiny eels in tanks with gravel strikes me as a virtual death sentence. Now, changing to sand is neither difficult not expensive. Silica sand (also known as silver sand) can be obtained at any garden centre for very little money. Choose the "smooth" not "sharp" grade for obvious reasons! A 25 kg (~50 lb) bag of the stuff costs about £3 ($6) at my local garden centre, so in other words there is no excuse for not buying and using the stuff. Plants love it, as do most fish. The main problem it causes is getting into the filter if big fish (like Plecs) splash it about. It can potentially become anaerobic if you allow organic material to decay under a great depth of the stuff. To avoid this, simply keep it clean, use Malayan livebearing snails to aerate the sand, or just keep the depth to a minimum, say, 5 cm (2 inches). If you go for the shallow sand bed approach, you obviously can't keep plants with roots, but epiphytes such as Java fern and Anubias are fine.> > my question is, I've tried both frozen bloodworms and live mealworms so far, both of which he has left uneaten. he appeared to smell the mealworms a little, but didn't eat any. I have been able to find live butterworms, waxworms, and Superworms, whatever those are, are any of these suitable food? or would I be better off trying earthworms? <Spiny eels are 100% nocturnal when imported, so be sure and put the LIVE bloodworms and/or Tubifex in at NIGHT. Remove anything likely to compete, such as catfish and loaches. Catfish and loaches are simply NOT at option with small spiny eels. Earthworms are also very popular with spiny eels, and perhaps the ideal reconditioning food for helping settle newly imported specimens in. Once you know the fish is eating, then you can wean them onto frozen alternatives. To be honest, spiny eels have to be close to the top of the list of fish that should be quarantined first so you can get them feeding before being placed in a community tank. They just aren't, by any measurement, "good community fish" -- they need a great deal of special care, and the vast majority of specimens die within a few months. Although basically hardy and very adaptable in terms of water chemistry, their demands for sand and live foods make them among the most difficult "common" fish in the trade. Larger species, ironically, are easier to care for, being indifferent to whether you use sand or gravel and being relatively easy to feed with things like earthworms, live river shrimp, or even (home-bred) feeder guppies. The small species, including all those sold as "peacock spiny eels" are simply difficult fish best kept by experienced fishkeepers in single-species or at least specially designed aquaria.> > there were also a lot of small snails in the tank I got him from, and I was wondering if he was maybe eating those, since he appears well fed. he looks like he's of a good girth, and explored all around his tank last night. if he has been eating snails, are they a good long term food source that I could maybe raise in a separate tank? <No, your eel isn't eating the snails. He lacks the jaw structure for that. Snail-eating fish tend to have strong jaws and flat teeth for crushing the shells: things you see on puffers, loaches, and certain cichlids and catfish. Spiny eels are nocturnal opportunist predators. They have deeply-cleft jaws that allow them to swallow surprisingly large prey. The smaller species feed primarily on worms and insect larvae, while the bigger species are more or less piscivorous (though in captivity are easily fed on prawns and other chunky invertebrate foods). > thanks! > Tori <Hope this helps, Neale>

Spiny eel system and food 05/31/07 Hi there! I found your site yesterday and have read about every page in it by now! Very informative, thank you! <Hi Tori. Im glad you like the site. You really read every page? By the way, it's good you collect information before buying.> My sister knows how much I love fish and so for my birthday gave me a five gallon tank with a filter and a picture of a spiny eel that she wanted to get me. I've just gotten around to setting up the tank (it's been running for two days now, with Watersafe) and I just added three artificial plants (is this okay since they will uproot them anyways?) and a cave structure, but when I asked about the fish themselves I was very disappointed to hear that they've only been fed normal fish flakes and been left to eat scraps that fall to the bottom, and most of the eels in the tank seem very lethargic. <Probably starving.> Are these eels likely to survive very long? <When they eat again: yes. If you think about buying one insist that you want to see them eat. Probably they'll only eat live food, if you are lucky they'll eat frozen food. If they do not eat, have skin diseases or stay lethargic leave them there.> Are they worth getting or should I look around for better cared for eels? Also, if I get them, will they take right away to food like freeze-dried bloodworms and such? <You'll probably have to start with living worms and hope that they start accepting frozen food one day. Most of mine never did. Freeze-dried food and flakes will not be eaten by most spiny eels.> I haven't found live worms anywhere yet, except fishing worms, but I'm a little afraid of the bacteria that may be on them, especially just starting out. <Earthworms or nightcrawlers from toxin safe soil are ok, too.> The pet stores around here seem to carry only freeze dried worms, but what is the best? (the eels are small, less than 5 inches). <All dried foods are most often not eaten by spiny eels.> Also, since it's a small tank (5 gallons), is it going to be too crowded with more than one eel or one eel and another fish or two? It'd be nice to have something to look at while my eel is hiding. <First you need to know exactly what spiny eel species you are talking about. Some only reach 5 inches, others 3 feet. For even the smallest species I consider 15 gallons per specimen is the minimum. See http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm and http://www.wetwebmedia.com/ca/volume_4/V4I3/SpinyEels/Spiny%20Eels.htm for more information. If you want to use the 5 gallon tank, it'd be best to consider some other fish species.> Thanks so much! Tori. <You are welcome. Marco.>

Spiny Eel questions... ID, sys., comp.   2/26/07 Hiya, WWM. This is Ashley again; the paranoid person with the two spiny eels named Hope and Doom. <Hi Ashley, spiny eel keeper Marco here.> I'm pretty sure they're what I've seen called yellow-tailed spiny eels. (Mastacembelus armatus) <I just had a look at your older mails with pictures and hesitate to agree, because the second picture seems to show that they have a separate tail fin in contrast to an unbroken fin. If that's right, they are not M. armatus, but a smaller species, probably Macrognathus pancalus (max. 7 inches). Have a look at the tail fin to verify.> They're still going strong, eating like pigs, and uprooting my plants. I have been considering "downsizing" in the fish department, since I have 5 tanks to keep up with now, along with tons of fish, and many other pets. <Thats just the beginning, you are already addicted> I was wondering if the two eels would be okay in a 10 gallon together (alone). I read somewhere that they stop growing at about 6 inches <Not if they are healthy M. armatus.>. I was thinking about either keeping them in a 10 gallon, or keeping just them, the gold dojo loaches, and the Pleco(s) in the 30 gallon. Which would be better? <If they are M. armatus, both tanks are too small in the long run, since these fishes will get 90 cm (35 inches) long. If they are a M. pancalus or another Asian species with separate tail fin, the 30 gallons would ok.> I'm also wondering if the activity of the other fish (various guppies, mollies, platies, the loaches, and the Pleco) affects the eels' activity level. They are fairly active during the day, and I'm wondering if I take the other fish out, will the eels' activity level go down? <To me it seems their activity is high, when the tank mates are peaceful, and low, when they are intimidating the eels.> Or do I just have some really weird eels? Thanks in advance for your reply, Ashley. <You are welcome.> Oh, and since they're fairly little, and don't even bother messing with anything bigger than a bloodworm, do you think they would harm 2 two and a half-inch Kuhli Loaches? I was told that they would attack them like worms... <They are probably safe with M. pancalus, but would be eaten by M. armatus>.

Re: A finicky eel? (no commentary?) <Hi, Pufferpunk here.> Ummm, was this supposed to have a commentary on it by one of the crew or was it just being sent back to me as an exact copy of what I sent? <We were having some kind of glitch with this email.  I did respond to you, but something went wrong.  I'll try this again.> A recent update: Over the past few weeks I've had a pretty stable setup in my 55 gallon brackish water setup. A nagging problem of how to get the ammonia, nitrate and nitrite contents down to nothing is my main problem. <Bio-Spira works wonders for cycling problems.> I still think that I'm overfeeding. <Definitely can cause re/cycling problems.> I find that odd even when I have an entire aquatic garden covering nearly the entire sand bottom. A total of 9 voracious adult mollies that devour anything and everything, only judging by taste if it's food or not. I don't understand how I could be overfeeding with how those guys devour food. <Food=waste=ammonia=nitrites.> Apparently of the fry I tried to save, 4 have grown up enough to swim freely amongst the others without fear. Meatball the Tetraodon nigroviridis has been growing steadily, and has actually taken to eating whatever variety food I drop into the aquarium. The two bumblebee gobies seem to be doing well, surviving with whatever bloodworms they can find before the mollies eat them all. I've had no problems aside from with a couple of guppies that I tried to add to the aquarium. When I put them into the quarantine tank, one guppy jumped right out of the water onto the floor on the first night, and the male counterpart died shortly after from fin rot. <Sorry to hear that.> I had also put in a weather loach, who had no problems at all. <Loaches are FW.> He ended up being called Jeac, reminding me of the cleaner shrimp from Finding Nemo. Jeac just cruises along the bottom vacuuming up the sand and siphoning out his gills as he goes along. The entire point of my email is a new inhabitant. The new addition is a spiny eel ( Macrognathus aculeatus), who originally went into my quarantine tank after buying him. It was a low salt content setup with a pH of 7.2, nearly insignificant levels of nitrates, nitrites and ammonia, and had plants to make it look like it had a use to it. After hiding himself under the sand for a little while, he stopped trying to hide at all. Not more than the next day I saw him lazily laying on the sand bottom, taking slow, raspy breaths. He was faded and his gills were a bright red color, and that's why I checked all the chemical levels. I couldn't figure out what it was so I risked tossing him into the big aquarium. I found it very peculiar because in the big aquarium I had JUST done a 40% water change because of a very high nitrate and nitrite level. Even afterwards the levels were higher than the quarantine tank, the salt was much higher with a hardness of 15, and a pH of 7.6. Oddly enough he has recovered, and is much more active. He hides in a log during the daytime hours, and is constantly out exploring at night. My main problem is that I haven't seen him eat anything since I got him, which was 3 days ago. I was told that they eat bloodworms as well, but he hasn't touched any of them when I squirt them nearly right on top of him, and in the end the puffer and the mollies eat all of them. Will he eventually start to eat or is there something still wrong with him that I have to fix to restore his appetite? <Although I have read in a few places that these fish can be kept in brackish, I think they do best in FW.  A little salt will probably be ok, except for the fact that you have a puffer that definitely prefers high-end BW-SW.  My 2 (6") adults are living in SW.  As far as your eel eating (for all I know, the problem has resolved by now after all this time... sorry), are you feeding live black/Tubifex/bloodworms?  Or frozen?  As these are wild-caught fish they are used to eating live food.  Also, some shy, nocturnal types are reluctant to eat in the light, so you may want to try feeding after lights out.> BUBBLES BUBBLES BUBBLES!..... My bubbles! (P.S. apparently I've become the second person in this entire area to have any expertise in brackish water aquariums, the fish compatible and especially the plants that thrive in that water. Looks like doing your homework pays off, although I have still not yet reached the holy grail of balancing the chemical levels in my aquarium. <Sorry to say, those plants won't fair well in high-end BW.  If your puffer is small <2", you still have some time before you need to raise the SG.> <I hope you get this response--Pufferpunk>

Sick eel please help I have a Aethiomastacembelus elipsifer Tanganyika eel and it does not look like he is eating and has gotten very skinny. I was wondering if there was anything I could do to fatten him up. He is not very active and does not look very good. I have him in a 55 gal. with mainly a Tanganyika/Malawi setup. I have tried feeding him bloodworms, freeze-dried plankton, and flake food at night after I have turned the lights out and the other fish have already been fed. I even tried holding it in front of him and he will not eat it. He used to bury himself all the time and now he just stays in one spot out all the time. I am very worried about him. What should I do?   < These eels are very cool. I saw many different species in lake Tanganyika as few years ago. They ranged from little small 4 inch eels that would swim around like little sea horses to very large ones like fire eels. In the wild we saw them feeding on small shell dwelling cichlids in around the rocks. We caught them at night in minnow traps using very oily fish as bait in the trap. I would catch the eel and place him in a separate tank that is well covered so he won't jump out. Place a layer of fine sand on the bottom and a rock or cave that he can hide in. Make sure the water temp is at least 80 degrees. I would first try some live washed earthworms or some well washed black worms. Then I would get some feeder guppies and throw them in the tank. See if the eel will take the guppies out of your hand. If this doesn't work then maybe small strips or raw fish cut to bite sized chunks. In a large community tank these eels are reluctant to feed because of all the commotion the cichlids create. You eel may end up needing live fish all the time. -Chuck> Thanks, Jessica B.

FW Eel for 20g Tank?  7/26/04 Hello <Hi, Pufferpunk here> I am sorry for sending you this letter but I have looked for days to find out about something.   <You don't have to apologize for asking questions, if you can't find the answer somewhere.> That something would be that I am looking to buy an eel and I only have a 20 gallon tank.  Would that be enough to have a eel.  If so you tell me which one or ones would be good to get.  If not could you tell me of something similar. <Most eels grow fairly large--way too large for the tank you have.  The only smaller eel that comes to mind is a spiny-nosed eel.  http://www.aquariacentral.com/species/db.cgi?db=fresh&uid=default&ID=0603&view_records=1  Even this eel will grow to 6".  Eels will only eat live foods, so be prepared to spend some $$$ on worms & such.>   Thank you Tyler I would really appreciate it if you would write back. Thanks <Good luck finding the eel you want.  ~PP>

Large FW Catfish fed feeders... I just found out you guys existed! Boy I could have used your help a long time ago. I didn't really have a question for ya, but wanted to tell you a story. I know you hear this a lot but I was also the victim of poor pet store knowledge (more than once) and ended up with a Pseudoplatystoma  corruscans (shovelnose catfish). <Cool cat, but very large with a larger mouth> The guy told me at the store that at about 6 inches the little guy was pretty much full grown. <LOL> I know now that that was completely false. Anyway we kept the little fella in our 33 gallon and he is was one of my favorites in the tank. Loved to eat and has really unique patterns. We were planning on keeping him till he got closer to a foot long. Unfortunately he never made it that far, he inherited what I think was a bacterial disease from some feeder comets, <Please, Please, PLEASE! No feeders unless you're willing to QT them. Garden worms and human seafood (shrimp, mussels, etc.) is far safer for these large cats.> even though we wouldn't have had him for very long I was really mad that he died so quickly (3 months). He quit moving around and had his feelers pulled back to his side. A usually quite knowledgeable fish keeper told us to just let it ride for a couple of days, thinking he might just be shedding, <Shedding??? Catfish don't shed there skin>> since he was the only one in the tank that was sick. He died the next morning. The other fish I was misinformed about is our fire eel. He lives in the same 33 gallon tank (don't worry I've treated the tank with Pimafix because whatever the catfish had it affected our leopard leaf fish, he got some body slime and cloudy eye but everyone is healthy now) and looking at your website I found out that he may get 2-4 feet long. The pet store told me he would be max a foot and a half. Right now he is just about a foot long and happily resides under a large piece of driftwood, coming out at night and to eat out of my hand, he loves frozen shrimp!<Great, safe food. But vary it somewhat.> I was wondering how long it will take for him to get too big for the tank and have to be given away. <Not really sure.> I'll miss him but it's not fair to cage him in such a small tank. <True> Will he really get 4 feet in captivity <possible, over 3 for sure.> or could we maybe get away with keeping him in a 100 gallon or more? <Would surely allow you to keep him far longer. Min. recommended size is around 80 gallons. Upgrade your plan to a 125 or 150 and you could have him for life.> Sorry to write you a novel. Pet stores should be forced to have accurately knowledgeable staff, the losers are the poor fish and pissed off purchasers. Don't rush to write me back, Amber <Don>

Ghosts, Knives and something else So how many of each Corys and/or loaches? <Say four to six Corys or three or four loaches. But as I said the loaches will get too big in time. You may have to trade them in at some point. And what are your thoughts on a tire track eel? <A tire track eel will get over 2 feet. Recommend min tank size is over 100 gallons. Don> Nicole

Fire Eel fdg., sys./comp.   4/1/06 Hi Crew! <Michael> Hope all is well in Wet Web land. I have a feeding issue with my 12" Fire Eel.  I purchased him 8 days ago from my LFS and since then I have not been able to get (him or her) to eat. <Happens... Mastacembelids don't like changes... and being "moved" is a biggie> (We will assume its a he).............  I have tried feeding him frozen bloodworms with no luck and have just tried frozen krill even though I could not find any documentation supporting krill to feed him. <Some will take... but takes training on to> He is in a 94 gallon corner tank with plenty of caves housed with a red empress, Hap Ali, sunshine peacock, yellow lab, pike cichlid, <These are aggressive species...> and 2 cats (4" and not sure the type).  All fish are between 4-5 inches.   I understand that there is some good competition for food for him and have found ways around that.  I have tried using a feeding stick to spear the krill and have used the stick which acts like a turkey baster as well to blow the bloodworms by him.  He has had ample time to eat both.  My latest attempt today was to put the bloodworms in a shot glass and to lay the glass in the tank (and yes, I took the Jack Daniels out of the shot glass first). <Heee, good idea to both> The bloodworms stayed in the glass and the cichlids left the food alone.  I left that in there for a half hour and watch patiently to see him not eat. I have read and re-read your archives and understand that they can go on hunger strikes for weeks at a time but I guess I would really value your input on my situation. Aside from not eating he does look healthy and acts fine. Thank you in advance for your assistance! Michael J. Bukosky <I would try some live worms... likely "black Tubifex" if you could find, or other... placed in a container as you've done here... but really, the best scenario is going to be to place this fish in a less-agonistic setting... completely covered top, with "soft" rounded substrate, diffuse lighting and soft/er, more acidic water than some of the fish you list prefer. I would do this move if this spiny eel does not feed within another week. Bob Fenner>

Peacock Eel questions... sys., comp.   4/26/06 Hello! I just found your site, and it's great! Anyway, I have a few questions. I currently have a peacock eel and 4 mollies (2 Sailfins, 2 Shortfins) in my aquarium. I have read in some places that Peacock Eels like brackish water, <Mmm, can tolerate some...> and so do mollies, but other places say that the Peacock Eel is completely freshwater. <Many Mastacembelids are brackish... not this one. Please see: http://filaman.ifm-geomar.de/Summary/SpeciesSummary.php?id=50400> Do Peacock Eels benefit from marine salt in their water? <Not much, no> How much salt should I add is this is the case? <A minimum amount...> Also, I have seen a 'Figure 8 Puffer' in my local fish shop, and was also wondering if this species is a suitable tankmate. <... no. Too likely to bite the mollies, spiny eel> I have also heard that they are brackish. <... please see WWM re> Any other information about suitable tankmates for my mollies and my Peacock Eel would be greatly appreciated! Paul <Paul... time to read my friend. Learn to/use the indices, search tool on WWM. Bob Fenner>

Some Questions about Spiny Eels - 05/22/06 Hi, <<Hello>> First off your site is very helpful and I have learned much from it. <<Is good to hear>> However I do have a problem that I couldn't find an answer to on Google or your site. <<Okay, let's see if I can help>> Im new to aquariums and about 5 weeks ago I purchased a Striped Peacock Eel. <<Read here and at the links in blue:   http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm >> At first he didn't eat much (actually hardly at all) but a couple of weeks back he decided to eat as much as he could get.  I would like to know how many 8-10 mm long pieces of earthworms an eel about 7-8 inches should safely consume each day. <<Hmm...would think at least 3-4 pieces would be fine.  Live Blood and Tubifex worms would be relished as well, and will add some variety to the diet>> Also he is outgrowing his home/cave rather rapidly <<Indeed, can reach a foot in length>> so should I try to find him a new hideout (the gravel is a bit to harsh for burrowing) or attempt to possibly put new finer gravel in his half of the tank (during a partial perhaps?). <<I kept some of these eels a few decades back (did I really just say that?!), quite interesting creatures as I recall.  A fine/soft substrate is best/ideal...along with some plants/hiding places...and subdued lighting>> I want your personal opinion/s as well a reasonable answer/s so that is another cause to actually Email you guys and gals. <<No worries mate...I hope I've been helpful>> Thanks in advance, Matt <<Regards, EricR>>

Some Questions about Spiny Eels II - 05/23/06 Wow thank you very much. <<Quite welcome>> I was feeding him as much as 8 pieces and before I decided enough was enough and he still wanted more lol. <<Yes, can be quite glutinous.  Best to feed smaller portions several times a day>> However I know they like to hide and that they like "soft" substrate, I wanted to know if it would be a good idea to change part or even all of the substrate during a partial water change or add a larger hiding spot. <<Would depend much on your filtration setup...but I think changing out parts of the substrate with partial water changes over the course of a week or so would be safest>> Thanks again, Matt <<Always welcome, EricR>>  

Hello!  I have an eel-related question. Mastacembelid ID, Sys.  7/9/06 Hello!  I've been frequenting your site for the last little while once I started getting fish and realizing that what the pet stores told me was for the most part completely wrong.  Your site has helped me tremendously with my Fire Eel (who I've had now for almost 3 months and he's doing extremely well :-) ) <Ah, good> but I've noticed there is a general lack of information on the "yellow-tail spiny eel". <Mmm... is sold under a few other common names... Most often as the Zig Zag eel on the U.S. west coast... Old scientific name is Mastacembelus panculus, now Macrognathus panculus: http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=10147&genusname=Macrognathus&speciesname=pancalus> I bought one of those about a month ago (he is also doing well, so whatever breed of eel he is, the care is much the same of that of a Fire eel.) <Yes> and he's grown a lot. <Good... though won't get as large... 9 inches is about maximum>   I got him when he was about 2 inches long.  I've looked at various pictures and he seems to resemble a zig-zag eel? <Ah, yes> Albeit slightly yellower, perhaps.  Anyway, I've included a picture so perhaps someone can tell me what it is, or if I'm completely wrong in my thinking that he is a type of zig-zag.  Thank you for your help, and I look forward to hearing from you! -Becki- <Does appear to be this species to me as well... Can make very interesting, long-lived pets... given initially healthy specimens, good care, consistent maintenance and feeding... As with all spiny eels, do pay particular attention to keeping the top entirely enclosed to prevent them exiting. Bob Fenner>

General habitat questions re Mastacembelids, Gouramis   7/26/06 Hi from New Zealand. Im planning to purchase 3 striped peacock spiny eels and have been searching the internet for 3 days solid trying to gather information. <Is about, but not easy to find... the Net will be much better... soon> Most sites contradict another one so Im all confused. I plan to have 9 Gouramis in the tank as well and two fake rocks that have lots of hiding places, some fake plants, low watt lights, Eclipse Aquarium Hood, and some walnut gravel as it has very small smooth pebbles. How many gallons will the tank need to hold? <Mmm, the "bigger the better"... at least 200 liters...> What dimensions do you suggest? <More "flat" than tall and narrow... to provide surface area for gaseous exchange, habitat for these types of fishes> Am I on the right track with my plans? I just want to get it right so the critters dont suffer. Thank you in advance. Emily <Please read here: http://wetwebmedia.com/FWSubWebIndex/matacembelids.htm and here: http://wetwebmedia.com/FWSubWebIndex/anabantoids.htm and the linked files above. Bob Fenner>

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