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FAQs on Mastacembelid, Spiny Eel Compatibility

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 Selection, Spiny Eel Systems, Spiny Eel Feeding, Spiny Eel Disease, Spiny Eel Reproduction,
By Species: Fire Eels, Peacock Eels, Tire Track Eels,


Compatibility between Ropefish and spiny eels     9/20/17
Hello to all and good afternoon!
I currently have two custom tanks, one 100x50x50cm 250l (40x20x20" 66g) and a 80x35x45cm 126l (32x14x18" 33g)
I have long since fallen in love with oddballs, currently I have a Macrognathus circumcinctus with some guppy and shrimp in the smaller tank it has around 10cm (4") or so, eating frozen brine shrimp very well, the bigger tank has some bichirs and a striped Raphael catfish (the bichirs are going to be rehomed, the catfish also might get out), I have ordered 3 Ropefish (Erpetoichthys calabaricus) with a friend, they are 20cm(8") according to him, the plan on the long run was getting more M. circumcinctus (getting a group of 4~6) and getting them together with the Ropefish and probably a African knife fish in the bigger tank, and probably a purple gudgeon or African butterfly for the smaller tank
Today though, it downed on me that the M. circumcinctus might look a lot like an earthworm to the Ropefish, and that maybe M. siamensis could work better for getting bigger, then I've been thinking of setting the smaller
tank for a group of M. circumcinctus and the bigger tank for the ropes, knife and M. siamensis, the bigger tank has a sump, a whole lot of canister media and is soon getting a fluidized sandbed, nitrate reactor and a little aquaponic setup, very well filtered, bioload wouldn't be a problem there, the smaller tank has a diy internal filter, so i wouldn't dare stock too much in it, it has a whole lot of Egeria densa though;
Now that my whole story is out in open, my main questions are:
Would Ropefish eat M. circuncinctus ?     9/20/17

If so, would I have a problem with doing M. siamensis instead ?
If not, how many would you consider a proper number for the tank ?
If I were to keep the M. circumcinctus in the smaller tank, could I get more to make a group ?
That should sum it up, I am free to any suggestion, thoughts on the setups and advices, the bigger tank is absolutely scape proof, the smaller has four 25cmx4mm openings at the top, I will soon take care of them though
<The short answer is that Ropefish are inept predators adapted to taking bloodworms and other insect larvae. While they can (and do) consume bite-size fish such as Neon-sized things, they are otherwise harmless, .
Assuming the Spiny Eel in question is similar in size to the Ropefish, it should be absolutely fine. An adult Macrognathus circumcinctus (around 20 cm/8 inches) should be okay, but I agree, Macrognathus siamensis (30 cm/12 inches) would seem better on paper, though frankly I've never seen any that size. Ideally, look for something like Macrognathus aral that get bigger, but not very much bigger, than the Ropefish. Here's what I'd do -- throw in a couple big earthworms and see what the Ropefish do. If they're devoured at once, there's your answer! As a rule, predators shouldn't be kept with tankmates less than 2/3rds their size, unless the potential prey is very obviously too well defended to be vulnerable. Cheers, Neale.>
Re: Compatibility between Ropefish and spiny eels      9/21/17

Thank you for the fast answer Neale, I guess I will just do that, try out with earthworms to see, in the worst case I'll just grow the M. circumcinctus in the small tank and when it reaches a nice size put it on the bigger tank...
<Quite so.>
Or even better, if I do find a M. aral I'll just let the M. circumcinctus chilling in the small tank and have the M. aral in the bigger tank
<Agreed -- M. circumcinctus is a great species for community fish that aren't too tiny -- Platies, Bleeding Heart tetras, X-ray Tetras, Harlequins, that sort of thing. M. aral is a nicer species for big fish communities, but without the territoriality of the Mastacembelus, as opposed to Macrognathus, species Spiny Eels. Cheers, Neale.>

Spiny Eel Compatibility       3/21/17
Good Evening WWM Crew! I have read the WWM page regarding Spiny Eel compatibility, and while the page was very informative, I did not find the answer to my question. I have a 75 gallon tank with three Rope Fish in
it. The tank has been up and cycled for 4 years now and is filtered by 2 Cascade 1000 canister filters (I'm all for over-filtering), and is set up for the Rope Fish. I use pool filter sand for substrate, RO/DI water with Equilibrium to replace minerals, Alkaline Buffer to boost kH, Acid Buffer to maintain a pH of 6.6 - 6.8, and Stability to keep my biological filter fully charged. I also have a tank cover that is both grated and smooth to prevent escapes. Haven't lost a rope fish yet.
<Good; they are escape artists>
The tank is fairly heavily planted (java fern, wisteria, and Rotala) with two large ceramic caves on opposite ends of the tank. But I recently read an article on Peacock Eels (Macrognathus siamensis) and was completely charmed by such a beautiful fish. So what I was trying to find on the WWM page regarding this fish is whether it would make a good tankmate for three Rope Fish.
<This Mastacembelid would be fine here>
Also, if it would work, would a Peacock Eel be happy as the only one of its species with the three Rope Fish or does it need others of its own kind.
<Is fine either solo or in a group>
I ask because although I have plans to move them up to a bigger tank, its at least 6 months away, and with the potential size of these species, I want to be careful not to overstock - even with the big filters. Your opinion would be greatly appreciated. Thank you!
<Welcome! Bob Fenner>
*Life is not about how fast you run or how high you climb, but how well you bounce. ~Vivian Komori*
*Renee *
Re: Spiny Eel Compatibility        3/22/17

Thanks again!
<Welcome. BobF>

Fresh water eels       12/5/14
I need any and all info on fresh water eels.

<Without a "please" or "thank you" you're unlikely to get "any and all" unless you were offering to pay. And even then, I hope you say please and thank you at the pub and grocery store!>
Also main point of interest, can they be in a 50 gallon with cichlids?
<No. That was easy, wasn't it! For the benefit of other readers: None of the freshwater eels, family Anguillidae, make good aquarium fish except when kept on their own in very large tanks. They are nocturnal, predatory, messy, grow to a large size, and are notorious for escaping out of tanks.
Best avoided. Spiny Eels aren't true eels of course, and the Tanganyikan and Malawian species are sometimes kept (by expert fishkeepers!) in Tanganyikan communities and (non-Mbuna) Malawian set-ups respectively. On the other hand, Spiny Eels are notoriously difficult to keep successfully, with most specimens ending up dead when casual aquarists buy them without understanding their very specific needs (sandy substrate, never gravel for example) and very fussy feeding habitats (worms and other small
invertebrates mostly, never flake/pellets, and no live feeder fish). Do read:
"Cichlids" covers a lot of ground so your question is so vague as to be meaningless. Some of the small species such as Macrognathus circumcinctus might be kept with Angelfish for example, quite successfully even, the two species largely ignoring each other (swim at different levels) but eat some of the same sort of foods (bloodworms, brine shrimps, etc.). On the other hand, only a lunatic would throw any Spiny Eel into a rough-and-tumble cichlid collection including things like Convicts or Jack Dempseys. The bottom line with Spiny Eels is you arrange the tank for the Spiny Eel, and only then choose appropriate fresh or brackish water tankmates. Orange
Chromides for example are salt-tolerant and would work nicely with Macrognathus aral, a species that's a bit less delicate if a little salt is added to the water (5-6 gram/litre). Cheers, Neale.>
Re: Fresh water eels       12/5/14

First off, i am horribly embarrassed by how rude my email was to you, and ya'al must think I'm a total POS. I would like to extend an apology to you. Secondly, best email response ever to a rude email. Thirdly thank you for this info, it'll help me a lot with my aquarium goals.
<Glad to help, and thanks for the kind words.>
P.s. They are the African cichlids that are super common at like big chain pet stores. Like your electric yellows, electric blues, the whites, etc. no jack Dempseys or flower horns in this tank, a 50 gallon would do a fish that nice and big justice.
<So, we're talking about generic Mbuna here, likely hybrids of "Pseudotropheus" for the most part. Mbuna aren't good choices for life alongside Malawian spiny eel species. The problems are aggression and diet, Mbuna being aggressive and also needed a greens-based diet rather than the high protein diet Spiny Eels need. Indeed, too much protein is, as I'm sure you realise, dangerous for Mbuna, which is why you use Spirulina flake as their staple not common aquarium flake. For sure Mbuna will eat the bloodworms and brine shrimps a Spiny Eel would need, but the results would be obesity, constipation, bloating, liver damage and other problems (kind of like what happens when humans eat too much steak and not enough salad).
I've also seen Mbuna (Yellow Labs, at that, which are "peaceful" by Mbuna standards) rip the fins from Bichirs, which are eel-like, so that's another reason not to mix them. I can't stress too strongly how difficult eels of all kinds are to keep. Choose an eel species -- Ropefish and Tyre-track Eels seem most widely sold -- then build the tank around them, removing or exchanging existing fish as required to create the right community. If you look over WWM, you'll find a lot of eel tragedies. Truly, many/most of eels (Ropefish, Bichirs, Spiny Eels, "freshwater" Morays primarily) wind up dead. In the right tanks all of these are hardy and easy to keep -- but the
right tank for them is very rarely a community tank, a cichlid community, a planted tank or even a jumbo fish aquarium. It's something very specific to their needs. To be honest, with eels, the best bet is a brackish or marine system into which a small Moray species can be kept, the marine species being particularly pretty. Cheers, Neale.>

Fire eel compatibility 2/3/11
I have a 90 gallon tank with 10 tiger barbs and 9 glass barbs in it. The tank has been set up since last November, and it was properly cycled, it has two filters on it, an Eheim 2217 and a Marineland Penguin 350B,
<Any filter like a hang-on-the-back filter that demands an opening at the back of the tank WILL allow the Fire Eel to escape. Stick with internal or external canister filters, and plug up all holes in the hood with filter
wool, plastic mesh or similar.>
water parameters normal, ammonia 0, nitrite 0, etc. I was wondering if a fire eel would be compatible with the barbs I have in there already,
or if the barbs would get eaten as soon as the eel gets big enough.
<Yes. Plus, if the Fire Eel is small, the barbs may nip at it, and once Fire Eels get damaged, secondary infections usually follow on.>
My local pet store's fish guy said a fire eel would be fine with barbs, and they should be getting some eels in tomorrow. Will a fire eel leave barbs alone? I have researched this and gotten mixed results. What's your opinion on this?
<Hope this clears things up for you. Do have a read here:
Spiny Eels are usually killed by their owners one way or another. Review aquarium security, substrate, tankmates, diet, and water chemistry before purchase. Cheers, Neale.>

Peacock Eel compatibility   2/8/10
Dear Crew,
I was wondering if a peacock eel (Macrognathus siamensis) would be ok in my 75 gallon which currently has 2 silver dollars one which is 6 inches, the smaller 3 inches, 3 rainbows which are 2- 2.5 inches, 4 roseline sharks ranging from 2 -3 inches, and a banded Leporinus which is 6 inches long.
<Oooh, do keep your eyes on this last. Leporinus fasciatus can be/come a very mean fish>
The tanks has some fake plants, driftwood, temp 79F. 2 400 emperor filters. Should I add an eel or should I leave the tank as it is? Thank you
for your help.
<Considering the mix of species you list, the likely water quality you provide for all, I think a Mastacembelid would do fine here. Do pay attention to making sure it is getting food on the bottom regularly. Bob Fenner>

Mastacembelus erythrotaenia question, comp.   9/21/09
I plan to put a Fire eel (Mastacembelus erythrotaenia), presumably 5-8 in.
(I have not yet purchased any of these fish), into a 125 gallon (long) aquarium along with a small Black ghost knife fish (Apteronotus albifrons), a Leopard Ctenopoma *(*Ctenopoma acutirostre), a Convict Cichlid (Archocentrus nigrofasciatus) (that already resides in the tank),
<Potential problem; rather aggressive species, out of all proportion for its size. Competition for hiding places will be stiff.>
a Rhino Pleco (Pterygoplichthys scrophus) (who already resides in the tank also) and six Silver dollars (Metynnis argenteus). What I am wondering is if I can keep two Angelicus Botias that already live in the tank with the Fire eel.
<Botia kubotai is boisterous and somewhat gregarious, and in groups of 5+ tends to settle down and mostly fights amongst itself. Two specimens are less predictable. Your main problems are feeding and competition for hiding places. On the feeding count, both Mastacembelus erythrotaenia and Apteronotus albifrons are very slow feeders, and unless hand-tamed, you're going to have problems making sure they have enough to eat. Ctenopoma acutirostre is also rather shy, and while ideal for use alongside the Knifefish and the Spiny Eel, combining it with aggressive cichlids and boisterous loaches is questionable.>
I know that you have said previously that they can not be kept together, but I have ample driftwood and plastic foliage (for the silver dollars), and more than enough space for territories, considering the only
territorial fish are the Ctenopoma, the Convict, the Black Ghost Knife and the fire eel.
<Territories won't make or break this tank; feeding will.>
I am also wondering if I could use very fine substrate (about the size of Kosher salt on a pretzel) for the eel. I can't use sand due to my syphon, which will clog.
<Keep the sand clean by stirring it, and then siphoning up the silt that appears.>
My last question: Can I use dried brine shrimp to feed it?
<Not a chance. Brine shrimp contain virtually no nutrition, and Spiny Eels will barely recognise live ones as food, let alone doubly useless freeze-dried brine shrimps. Spiny Eels, as well as Black Ghost Knifefish,
are strictly live food fish initially, and subsequently wet-frozen bloodworms, lancefish, prawns, etc. If you can't offer these foods, don't keep them.>
it will be receiving chopped earth worms a few times a month, along with feeder fish occasionally.
<Don't use feeder fish, ever. Your research has presumably informed you that Mastacembelus erythrotaenia is super-sensitive to bacterial infections. Adding something as disease-ridden as a feeder fish to a Spiny
Eel tank is just plain suicidal.>
Do you think, under these conditions, it will thrive?
<Probably not.>
My P.h. is around 7.5-8.0.
<Would be less worried about pH and more focused on water quality when keeping these fish. Apteronotus albifrons for example needs fast-flowing, not too warm water with lots of oxygen. Even relatively low levels of nitrate, and any kind of nitrite/ammonia, will cause stress. It's a fish that lives in shallow, splashing water across sandy substrates. Bear that in mind, and plan your tank accordingly. Conversely, Ctenopoma are
swamp-dwellers, so you need to create areas with still water *at the surface* where the Ctenopoma can lurk; bunches of floating plants, real or plastic, work nicely.>
Thanks! -Jack
<Cheers, Neale.>

Re: Mastacembelus erythrotaenia question  9/21/09
Thank you for all of the great advice! I plan to buy my fish in about a week, and plan on giving away the Convict cichlid.
<Probably best.>
The Angelicus Botias will be moving to another tank.
I *will* be using sand for them, thanks to your tip on syphoning.
<Turkey basters are also very good for "spot cleaning" sand when you don't want to drag out the siphon.>
I'll use many floating plastic plants (second hand from a Gourami) for the Ctenopoma. I've heard before that you can use a turkey baster to get food down to eels. Is this true?
<Can work. I use long forceps to feed fussy fish, and tame them. Spiny Eels are very intelligent, and should become tame quite soon. They love earthworms more than anything else on Earth!>
I plan on trying it, so the silver dollars don't gobble it up before the fire eel has a chance.
<Good plan. Since Spiny Eels are nocturnal, leave out frozen bloodworms and other such foods during the night, and if they're the only predators in the tank, they should consume. Spiny Eels and Black Ghost Knives should compete at about the same level, so I'd expect them to coexist.>
And if all else fails, could I use a divider to separate the Knife fish and Ctenopoma from the eel to feed them?
<Hassle. Get everyone tame, and hand feed. Ctenopoma will take floating blocks of bloodworms happily during the day, so they're easy. Tame the Spiny Eel, and then feed the Apteronotus partly at night, and partly with foods it can gobble up quickly during the day.>
My tank gets a weekly %50-60 water change, so I don't think nitrate will be a problem (But if it *is*, I could increase water changes to twice a week).
Thanks for all of the help! -Jack
<Good luck! Neale.>

Re: Mastacembelus erythrotaenia question  9/21/09
Hi, Jack again. Let me just say that all of your information has been great.
After reading your replies to my earlier questions, I looked at a few videos of full grown Mastacembelus erythrotaenia feeding and swimming. And that's when it hit me: This is going to be a gigantic fish.
<Potentially. Takes a good long while though, and assumes it's kept properly, something one learns not to take for granted with Spiny Eels...>
In my 125 gallon tank, with a Black Ghost knife, six silver dollars, and a Ctenopoma. What I'm wondering is if I can keep it in a tank like this without it feeling cramped or miserable.
<Depends. 125 Imperial gallons is 150 US gallons, and a 125 Imperial gallon tank should be ample. But 125 US gallons would only be good for a single specimen, and by the time you've squeezed in the Knifefish, the Climbing Perch and the Silver Dollars, it would be a bit crowded. Still, you'd be fine for the first few years, and only once the Fire Eel reach the 60 cm/24 inch size would upgrading the tank be a pressing issue. Adding a sump and providing robust filtration would help.>
I know that they are a very intelligent fish, and I really, really don't want to be one of those people who gets a fish because it's cute, only to learn the hard way that it grows huge (I admit to once buying a red belly
Pacu, thinking it would be "Cool" to have in my 30 Gallon tank full of Neons and sword tails. Pet store told me it would only get 6"). So, could I get the magnificent Fire eel, or would I have to go with something else?
<The Tyre-track Eel stays a bit smaller, and the One-Stripe Spiny Eel (Macrognathus aral) even less, to around 50 cm/20 inches at most. This latter species is fairly widely sold, though often under the wrong name, so shouldn't be impossible to track down. If all else fails, the Senegal Bichir (Polypterus senegalus) or Marbled Bichir (Polypterus palmas) are both fairly small, at around 35 cm/14 inches at most, but characterful and peaceful towards things they can't swallow whole. Either would be a cracking addition to your big fish community. They do tend to get nipped by cichlids and tetras, but Silver Dollars should be fine and Ctenopoma acutirostre certainly is, because I've kept them together myself!>
<Cheers, Neale.>

Stingrays and eels, FW comp.  05/03/09
Hello, Forgive me I am just getting into this! I have a 250 gallon tank in which I am setting up for freshwater stingrays. Now the man at the store said I can put a fire eel in with the rays, is this true? I want to do this
all right I don't want to take any unnecessary risks with my tank. I was wondering what the best plants I can put in are? The store recommended I get a fire eel, stingray and some Arowanas, is this a smart mix or fish? I was also considering an Oscar. Any other advice for the newcomer? Thanks for your time. Scott
<Hi Scott. The short answer here is that the larger Spiny Eels, such as Fire Eels and Tyre-track Eels, have been kept with Stingrays successfully.
That said, the usual warnings apply. Fire Eels are finicky feeders, and usually do best in tanks where they can be hand fed. Since both Stingrays and Fire Eels enjoy earthworms and river shrimps on the substrate, you want to make sure both are getting enough to eat. There's also the usual problem with Stingrays that if they get scratched, they can get very sick; Spiny Eels are nothing if not scratchy! Spiny Eels also need hiding places; by preference, sand they can dig into, but that's not something we usually encourage in Stingray tanks because of problems with hygiene. So you'll need some hollow ornaments (e.g., PVC tubes) where the Spiny Eel can hide, but that'll take up space from the Stingray. So while it should work, there are issues to bear in mind. Stingrays, Arowanas and Oscars usually get along extremely well. Final advice? Be sure and buy, read a book on Stingrays. These are expensive and very delicate fish, and most people fail. Be prepared! Water quality is the issue, and for the first few months, I'd recommend introducing a single Stingray into a fully cycled tank, and leaving it alone while you feed it and generally get used to managing the low levels of nitrate you need. Remember, every additional big fish essentially means you need to do twice as many water changes, and at some point, this will get annoying! Cheers, Neale.>

Peacock Eel Companions   3/9/09 Hello All! <Ave,> I have read that loaches are not good companions for spiny eels because they will bully the eel and keep him from eating. Can you please be more specific? I have 4 Black Kuhlii Loaches in the same tank as my peacock eel along with four mystery snails. Assuming the tank is big enough, I have a sandy substrate and the food is plentiful, do I have anything to worry about? <Kuhli loaches (Pangio spp.) would be exceptions, and assuming the Macrognathus species you have was reasonably large, I'd expect it to compete well. The problem loaches are the fast-swimming, semi-aggressive, often territorial species, i.e., the majority of loaches! Dojo loaches, Skunk loaches, Red-fin loaches and so on.> I have another question. I bought another peacock eel about a week ago because I heard that it is better to have more than one. Is this true? <For Macrognathus spp., yes, they are sociable. Mastacembelus spp. eels by contrast are territorial. Peacock eels are usually Macrognathus siamensis, though of course your retailer might stick the name on who-knows-what!> Anyway, I put him in the tank and I have never seen him again. I have a hood covering my tank and the only hole is the space around the filter and I took a fine netting and velcroed it all around the filter and the hood so they can't get out and I have fixed it so that the door that I open to feed them does not open easily. Also, because I know things happen I looked all around my tanks and basically the whole room and cannot find him. <Hmm... notorious jumpers, escape artists. If he jumped out, he may have been eaten by a cat or dog? If he couldn't escape, he's probably still in there somewhere.> The reason I know he is absolutely gone is because I had both eels in a tank with a handful of dwarf gouramis, 3 snails, and 4 black Kuhlii loaches, and since I never got to see the eels and the loaches because they hid all the time, I took them out of the community tank and put them in another tank; I scooped out all of the sand from one tank and put in in the other tank and only came up with one eel. Actually, it's pretty funny (not really funny) because I thought I only had 3 loaches and found out I had four, but now am missing one eel. Any ideas? <Well, he's either jumped out (likely); still in there and hiding; or died, was eaten, and now just bones. Nothing it could otherwise be.> Also, is it normal for spiny eels to rub themselves against plants and the heater and the snails (I have even caught one of the snails on top of him!) <They do like being in contact with solid objects or the substrate, yes. They also like being tangled up in floating plants. If they "rub" themselves as if itching, that's something else, and possibly a sign of Ick.> This can't be normal, is it? And he really buddies up with the loaches. Is this normal? <Likely less about friendship and more about Spiny Eels and Kuhli loaches both appreciating the same things in life: burrows, shade, hiding places.> I know that when fish start rubbing against things it could signify problems, it this also true with eels? <Can be, yes.> Lana <Cheers, Neale.>

Fiddler crabs versus peacock eel  10/21/08 Hi <Hello,> I have a freshwater tank with three gold fiddler crabs, one male and two female. <Uca spp. are brackish water animals... don't last long in freshwater conditions... On the plus side, at least some Spiny Eels tolerate brackish water well, and may even be healthier in it than freshwater.> Well I got a peacock spiny eel, who was about 5 inches, and the next morning he was being eaten by the female crabs. <The eel died; the crabs ate the corpse. Spiny Eels die very easily, frequently from bacterial infections. For example, they can't be kept in tanks with gravel. Must be sand. Gravel scratches the skin, allows bacteria to get past the mucous layer, and within days they die. This happens SO OFTEN that it is depressing. Brackish water around SG 1.003 (as opposed to "teaspoon tonic salt per gallon" nonsense) may be beneficial to Spiny Eels because it minimises the risk of bacterial infections.> I don't understand what happened. He was perfectly fine all day long... and I know that my tank is in great condition. <Do you have sand or gravel in the tank? If gravel, that's likely part of the issue. Spiny Eels are also easily starved. You can't keep them with things like loaches and catfish because they don't compete for food. If you stick one in a community with loaches and catfish, it will get steadily weaker with time. They obviously don't eat flake or pellets, and need a meaty diet of things like earthworms or frozen (not freeze dried) bloodworms. Just getting food into them is hard enough without keeping them with other nocturnal fish that steal the food first.> Is it possible that the crabs could have killed the eel? <No. Uca spp. are primarily detritivores, though they will eat carrion.> The eel was somewhat slow moving and was still very young. I am very upset about the eel, it was very beautiful and I would really enjoy having an eel in my community tank. <Sadly, these aren't "easy fish" and I'd encourage you to read my thoughts here before doing anything else: http://www.wetwebmedia.com/FWSubWebIndex/spinyeelsmonk.htm > Ashley <Cheers, Neale.>

Re: Fiddler crabs versus peacock eel 10/21/08 Thank you so much for the fast response! <Most welcome.> Well I do have a sand/gravel substrate, however the aquarium store had large gravel. <Hmm... in my opinion, plain smooth silica sand is the way to go, particularly with small (sub-20 cm) specimens.> And the eel was buried in there when I got it. Do you think it is possible that the eel got the infection at the store? <Quite possible.> I watched the eel quite intently and he never buried himself. <Possibly prefers the hiding places available above the substrate. In any case, they feed by pushing the rostrum (the "trunk" on the nose) into the sand to uproot insect larvae and worms. So even at that level, sand helps.> He actually spent most of his time swimming near the top of the water. <They do indeed like swimming among the roots of floating plants. They're great escape artists though, so be warned that they're also apt to jump out, if they can.> Also do you have any suggestions on what I could do to get my tank better prepared for a peacock eel? <Do read my article; that's everything I know about them!> I have three small Cory cats, will they be a problem for the eel? <Does rather depend on the size of the tank and how much food you put in. Assuming you were generous with the food, these fish might get along just fine. The real problems come with "bullies" like loaches and Plecs that will keep the Spiny Eel away from its dinner. Earthworms are the secret to success with the Mastacembelidae, and they will thrive on these tasty morsels.> I guess I should let you know that I have a 55 gallon tank with a mostly sand substrate. There is some small white gravel mixed in with the sand. <Hmm...> I have got platies, swords, mollies, tiger barbs, 2 rainbow fish, paradise fish, the Cory cats, and the crabs. Everybody lives perfectly fine together. I usually put a small amount of aquarium salt in the water. Would this be recommended for an eel? <I suspect the Fiddlers are on borrowed time. They're amphibious and will spend all their time trying to get out. The vast majority of specimens in freshwater aquaria last but a few months. It's a shame they're sold at all, to be honest. Adding "small amounts of salt" won't really have much effect either way. They won't make any of these animals healthier, but if you want to waste your money on boxes of salt, then go ahead, you aren't doing any harm either.> Ashley <Cheers, Neale.>

Re: Fiddler crabs versus peacock eel   10/21/08 Well thanks again...I know the crabs need air every now and then. <No, it's not "air now and again" for these crabs. They're land crabs. They live, feed, socialize on land. They only go into the water to moisten their gills and to breed. That's it. Otherwise they're as much land animals as, say, frogs. When kept properly they spend 95% of the time on land. The males are very cute, standing about waving their giant claws to scare rivals and flirt with females. This is why they're always trying to escape: it's like trying to stop a bird from flying away.> I have an external power filter and the crabs climb up the tubes. But i have built a plastic mesh enclosure so that the crabs can get to the air but not fully escape. <Sooner or later, crabs escape. I say this as someone who had to get his parents to take apart their kitchen units to rescue a Cardisoma crab when I was a teenager! The thing was the size of a softball and yet managed to escape...> I read your article and it definitely gave a lot more knowledge about the eels. I do believe that if I try eels again I will get the gravel out and get some live worms... You've been most helpful! Ashley <Happy to help. Enjoy your fish. Cheers, Neale.>

Fire Eel and Discus 05/19/08 Heya For the last 6 months I've had my Fire Eel happily living alone in a 90 gallon tank. it is planted (there's java fern growing on the bogwood). I want to add 4-6 discus to the tank, I double checked PH and temp and it is in a discus range (the Eel seems much happier in a warmer environment). In your experience would discus be compatible with the fire eel? and what number do you recommend, 4 or 6? when they get big I plan on setting up a 150 wide for the discus if they do outgrow the 90 gallon. Jessep <In theory Spiny Eels could work with Discus. There shouldn't be much competition over food, and the Discus are far too large to be eaten by a hungry Spiny Eel. But Fire Eels are VERY big fish once mature (expect 75-90 cm/2.5-3 feet) and that alone may terrify the Discus. So a lot will depend on how big the Discus are relative to the Spiny Eel. My gut feeling is that this wouldn't be a long term plan, but a juvenile Spiny Eel with some full grown Discus might work out for a few months. As for keeping Discus, six seems to be the magic number as far as avoiding aggression and ensuring you get a breeding pair. Cheers, Neale.>

Fire eel compatibility 5/16/08 Hello all, I have just one question. I have a 65g tank. At this time I have 4 paradise Gouramis, 1 gold Gourami, 3 Rainbow fish, 1 African Brown Knife, 1 red fin shark, 1 rainbow shark, 1 Pleco and 1 blood parrot. I was wondering if I could safely add a fire eel? <No; quite a busy tank already, and too many of these fish will compete for food and space. Fire eels are very sensitive to poor water conditions, and you really need a 100+ gallon to give these fish even a chance of thriving in captivity. Most specimens die within months of import. Should the fish survive to adulthood, at least some of these fish would be eaten. Have made the mistake of combining a Tire Track Eel with Swordtails, which you'd assume would be safe. Nope: quickly eaten without any difficulty! Do read my article on Spiny Eels, here: http://www.wetwebmedia.com/FWsubwebindex/spinyeelsmonk.htm> I am planning on replacing the gravel with sand if I add the eel. <If you want an "eel", better off with, for example, Polypterus senegalus, one of the toughest and most easy-going Bichirs.> Thanks for all of the great info. you all provide. Wet web media is by far the best sight I have found for info. on the great hobby of fish keeping. Keep up the great work. Thanks, Virginia <Thanks for the kind words. Cheers, Neale.>

Spiny eel comp.  - 1/24/08 Hello there, I hope its ok to e-mail you directly. I have had smaller tanks in the past. 2 weeks ago I got a gently used 55 gal. tank. It came with a stand, 200 watt heater, and a EHEIM 2213 canister filter. I have made up my mind that I would build the tank around the three things that I have always wanted to have in a tank. First was that I have always wanted to have a spiny eel, the second was sand in the tank and the third where things like snails and an upside down cat. <In theory a good idea, but I'd make the point that Spiny Eels are difficult to feed, and it's best to settle them in and get them tame enough to eat readily before adding catfish or loaches.> I have visited several forums, scientific info sites, and I am a little overwhelmed because I seem have lots of info but none of the answers I am really looking for (this could be because I haven't figured out the right questions yet.) So thus I turn to you ... I would like to hear your opinions, hear what you have observed, and just talk to people that have actually owned eels. <We have a stack of articles on Spiny Eels, do start with these: http://www.wetwebmedia.com/FWSubWebIndex/spinyeelsmonk.htm http://www.wetwebmedia.com/ca/volume_4/V4I3/Spiny_Eels/Spiny%20Eels.htm > Question 1 Which eel(s) would be most appropriate for a 55 gal. tank? <Almost any of them, though I'd suggest the Tyre-track Eel (Mastacembelus armatus and M. favus) and Fire eel (M. erythrotaenia) would do better in larger tanks.> Question 2 What type of plants are best to be added to the tank (what plants make the eels most comfortable, do eels do best around, and do well around eels?) <Because Spiny Eels burrow, the best plants are epiphytes (Java fern, Anubias, etc.) and floating plants (Ceratopteris, Hornwort, etc.). Spiny Eels particularly like floating plants that make a big mass of leaves and roots at the top of the tank. If nothing else, floating plants seem to encourage them not to go leaping out the tank. If you want rooted plants in the substrate, I'd go with robust, shade-tolerant things that won't mind all these floating plants. Hardy Cryptocorynes like C. wendtii would be ideal.> Question 3 What type of decor and ornamentation is best (for providing hiding spots and would be appropriate?) <Not terribly important. Floating plants are good because the spiny eels will "burrow" into them where you can watch them. Hollow ornaments are also favoured. Plastic or ceramic logs are probably the ideal. Rocks and bogwood aren't terribly important, particularly if the Spiny Eels have lots of sand for digging into.> Question 4 Tankmates: What fish go well with eels? I have read that they might eat smaller slower fish and understand that what Im more interested in are what are good tankmates that can co-exist without pestering the eel(s)? {Having read about fin nippers and eel pesterers and not having them defined.} <Anything too big to swallow will be safe, as Spiny Eels aren't aggressive towards other fish. Mastacembelus species tend to be mutually territorial, so they're usually kept alone. Macrognathus species are more sociable, and often work best in groups of three or more. Rainbowfish and gouramis are excellent companions for Spiny Eels; you can also choose any of the peaceful barbs and tetras, for example Golden Barbs or Bleeding Heart Tetras. If you have hard water, then large livebearers are a good option, things like Swordtails and Mollies (the latter especially if you're keeping your Spiny Eel in slightly brackish water). The fish to avoid are anything small and narrow (like Neons or Danios) as these may be eaten, and anything that will compete with them at night time for food (such as catfish and loaches).> Any advice you could give me or if there is anything you think I should consider I would appreciate hearing back from you, Chris <Hope this helps, Neale.>

Tiger Barbs and peacock eels, comp., Mastacembelids gen.    1/5/08 Hello WWM! <Hello.> I am new (2 months) to freshwater aquariums. <OK.> I was wondering, will 2 Tiger Barbs and 2 Peacock Eels get along when in the same 10 gallon tank with limited places to hide and some live aquatic plants? I'm concerned since both are aggressive species. Will they fight? <Won't work. Tiger barbs are schooling fish and become nothing but trouble when kept in groups of less than six. They nip at other fish. So, get six Tiger barbs before you start fussing about other species. Six tiger barbs need more than 10 gallons of tank space. At least a long 20 gallon tank to get the room to swim and play they need.> Also, will Peacock Eels eat spikes (fly larvae), sinking shrimp pellets, freeze-dried blood worms, Tubifex worms and worms you use as bait when fishing? This is what I've been feeding them, but can't tell if they are eating or not. <Peacock Eels, by which I assume you mean Macrognathus siamensis, will eat live and frozen worms/insect larvae happily enough, but ignore dried foods, pellets, etc.> I just got my Tiger Barbs yesterday and they just seem to hang out together. <Why did you buy just two? That's mean. These are social animals and as they mature they create a pecking order. Denying them this leads to problems. Besides, they're too big for a 10 gallon tank. If you have access to January's edition of TFH Magazine, I have an article in there all about stocking 10 gallon tanks. Consider this essential reading!> So far, I've had 3 Striped Peacock Eels (one died when it was exploring its new home and it was eaten by my filter) they get along fine. <Please let me make this very clear: Peacock Eels are not easy to keep. For a start, they CANNOT be kept in tanks with gravel. Putting them in a tank with gravel is giving the eel a death sentence. These eels dig, and gravel scratches them, and then they get secondary bacterial infections, and then they die. I have seen this and heard about this too many times over the last twenty five years of my keeping tropical fish. Secondly, they are difficult to feed. Live foods are preferred, and they CANNOT be kept with any night-time bottom feeders. Neither catfish nor loaches. You must feed the eels at night, and they must be the only fish in the tank eating the bloodworms or whatever. Otherwise they starve to death. Finally, they jump out of tanks. Again, this is incredibly common when people keep these eels. The tank must be almost airtight. Block any holes big enough for the fish to squeeze through.> I also had 2 Pictus Cats and a Pleco not survive, any ideas why? <Your tank is insanely overstocked. A Plec will reach 45 cm, probably longer than your aquarium! Pimelodus pictus is a schooling, riverine catfish that needs to be kept in groups in a tank with lots of water current and swimming space.> I took a peek at your FAQ's and noticed there were quite a few articles about eels! Good Job!!! Just out of curiousity, how long have you been studying eels? <Studying them may be overdoing it a bit, but I kept my first Mastacembelus armatus back in 1988, and have been keeping and writing about them ever since.> Also, how are you supposed to determine the sex of Peacock Eels and Tiger Barbs? <Spiny eels are universally sexed by looking at their body shape: females are dramatically more deep-bodied than the males. Tiger barb females are rounded at spawning time. If you have a group of six or more mature fish, it's usually not a problem to identify the males and females.> Any advice would be greatly appreciated. Thanks, a curious newcomer. <Good luck, Neale.>

Geophagus Sucking on Fire Eel?  11/15/07 I am sitting here watching my 150 gallon tank and I am seeing one of my Geophagus sucking on the fins of my 3.5 foot Fire Eel - <Neat!> What's up with that? The eel is prowling the surface hoping it is dinner time - an does not even flinch while the Geophagus is sucking on his tail fins... <Mmm... how to state this... fish mucus has many properties... of use to its producer, and is a food source to some other organisms. In this case, your Eartheater> I assume it is sucking cause there are no bite marks or scuffing. Any thoughts? Tim <If causing no damage, I would not be concerned... the Mastacembelid can take care of itself, assuredly. Cheers, Bob Fenner>

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. <That's 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>.

African cichlids and eels??, Eels & Rift Lake Cichlids hey, would a fire eel work in a mixed African rift lake setup?? I currently have a 1-2" frontosa, 2" Malawi blue dolphin, 2 3" Synodontis multipunctatus.. if it doesn't work, r there any other eels that might survive in this.. can u recommend any?? Thanks, Jiwan.. <Well- "survival" is a relative word. Although Fire eels are adaptable to a range of water conditions, I'd probably pass on adding one to this system. Your Frontosa is gonna be a BIG fish, and the other fish can be fairly aggressive feeders. Fire eels also get big -more than 3 feet-but they are generally nocturnal and are not competitive feeders. For more info on eels, see ://www.wetwebmedia.com/FWSubwebIndex/matacembelids . Good luck! Scott F.>

Black Shark and Fire Eel - Out of the Frying Pan and Into the Fire! Hello, hope you can help me!   <I will indeed try.> I have been looking for quite a while and trying to decide what to purchase for my tank or if I need to buy a larger tank if it is needed!  I am wondering if a black shark 2" long and a fire eel 9" long will be good tank mates? <No, black sharks (Epalzeorhynchos bicolor) are said to be very hostile fish.  I've read many sites saying how their red tailed Black Sharks have really hurt some tank mates.  I would think that it would pester a fire eel.> I know that black sharks are aggressive, but are they to aggressive if they grow together! <They will eventually be mean... their nature won't allow them to be nice forever.  No sense putting an eel through that. Here is a quick bit of info on the black sharks.  http://aquarium.wendellarhoads.com/blshark.shtml They seem to list what had happened to their tankmates.> I have heard and red that balas, red tailed sharks, or rainbows and good possible tank mates,  what about black sharks?   <larger rainbows wouldn't bother an eel at all.  The others you run a risk.> Would a lot of hiding places for the eel make a difference or keeping the black shark well fed make a difference? <It would help, but wouldn't take care of the underlying issue that the fish would be mean to the eel.  I suggest that if you want these two fish, you think about having two separate tanks for them.  Then you can enjoy both without worry.  Good luck -Magnus.> Help Needed!!!  Thanks CHO, IA

Puffers I have one question, but first here is my tank set-up. 20 gallon tank with whisper filter and heater (it always stays at 76.5 degrees) inside are two dwarf puffer and three Buenos Aires tetras. I want to add a fire eel. Can I? What I mean is can I add the eel with out It killing the puffers? <No, I wouldn't add that to the tank, I really think that a fire eel will try to eat the dwarf puffers.  Even if it doesn't eat them, it will surely stress the tiny things out.  I would suggest setting a tank specifically for the eel if you really want to get one.>

African cichlids w/ eels I have been doing some serious research about this and have unfortunately gotten (as usual) conflicting advise on the matter.  First off I love the site, great answers.  What do you know about Aethiomastacembelus elipsifer or Aethiomastacembelus plagiostoma? <Not much. Members of this genus of spiny eels rarely come into the trade in the west> I have an African setup in a 55 gallon w/ black sand and tons of rocks to hide in.  Do you think these guys would do well?  I know to cover any and every hole to prevent suicide and thought about actinic lights  to possibly increase the time spent swimming instead of hiding.  Tell me what you guys think. Thanks, <If the cichlids are not overly aggressive... and you can get the eels in relatively good initial health... you just might have a very nice biotope set-up going. Please write in re your experiences with these Mastacembelids. Bob Fenner>

Freshwater eel Hi there, crew.  It's been a while since I've written.  Last we "spoke" I had gone freshwater only.  I found good homes for my SW fish and corals, and now have a 180 oceanic with a huge sump and bio balls.  I keep the tank at 80 F, and I am using an Iwaki RXLT 40 full blast for sump return.  I do a 30 gallon water change once a week, and clean the overflow sponges at that time.  I run a 40 Watt Aqua UV light on the tank, and use a diatom filter once a week at water change time.  The gravel is a little on the large side, and not really conducive to burrowing.  There are a lot of rock caves, though.    I have four clown loaches (2 are 8+ inches [13 years in my care, so far] and two are 2 inches); 2 small Corys, 9 glass catfish, 2 Plecos.  I was thinking about adding a spiny eel (after lengthy quarantine, of course).  What do you think?  I have read your FAQs, and would like to know what kind of eel might go well in that tank.  I also have another tank (80 gal) with just a couple of dwarf Gouramis that I could place the eel in (he's going to start there, anyway).  Would be interested in recommendation for a fish that did not grow too large and would not eat any tankmates.  I feed frozen bloodworms, mysis shrimp, flake food and sinking pellets.  My loaches are pretty old and hefty, so I assume that they're happy with the diet. thanks for your help, tom Dear Tom; Tire track eels grow to two feet, and will eat any tankmates that fit into its mouth. Likewise fire eels. There is a pretty eel that grows to around 4 inches called the Short finned spiny eel (Latin name is Mastacembelus zebrinus) if you can find one for sale. Many other eels are either aggressive, grow large enough to eat your other fish, or are brackish/marine. Here is a link for ya: http://saltaquarium.about.com/cs/eelprofilesindex/a/aa082901.htm -Gwen

Purchasing some spiny eels I was thinking about purchasing some spiny eels from an online store. Is it wise to have a striped peacock, a Zig Zag, and a fire eel all in the same tank? <Not problematical in terms of them getting along, feeding/foods, having different habitats if this is what you mean> Also, the site I was planning on ordering from said that spiny eels eventually needed 29 gallon tanks... but I read about people having to put them in 100 gallon tanks, what's the minimum size I can have for one and does it affect what size of tank I need if I have one of each of the aforementioned spiny eels? <Mmm, at least a hundred for the Fire Eel... gets quite large over time, in good health... the others could live in 29 gallon systems (well-covered!). Please read here: http://www.wetwebmedia.com/FWSubWebIndex/matacembelids.htm and the Related FAQs (linked, in blue, at top)>   I read that the eels will eat crustaceans, so I assume a blue crayfish would be a bad tank mate...  Is it wise to order online?  Or would you suggest going to a local breeder or distributor?  Thanks in advance. <Both sources could work... or be trouble. The spiny eels are quite tough if cared for well, and doomed if not... Seeing them ahead of purchase is definitely a bonus, better start if you can find, order them locally. Bob Fenner> Trapping Spiny Eels Dear Crew, Would any of you have any experience in trapping eels? I have a 240gal. acrylic tank that I want transfer my Discus and Angels and Clown Loaches to.  In this tank are several Leleupi Cichlids, Dnobnoi and a large clan of Brichardi so I will have to take all the rock and wood out anyway. But, as you know, the eels will be able to go under the gravel.  The gravel is 4 to 5 inches deep and supports a jungle of Giant Val and a variety of other plants I would rather not have to rip up (their roots are a mass of tangles).  Also, there are LOTS of eels.  I had put just two in.  Now,  what are the odds that the 2 eels I bought were male and female!!!  Or are they able to change sex to fit the situation?  At first I was so amazed, and thrilled, to see the cutest little baby, but they just kept coming!  I think there must be at least 5 generations in there.  I think the smallest might be catchable because they don't seem able to get under the gravel and instead live amongst the plants and wood.  However Mom and Pop and several of the teenagers disappear with no trouble at all.  Any suggestions?  Thank you for any help you can offer. < WOW, WOW, WOW. If these are true Lake Tanganyikan eels this is the first incident I have heard of. African eels are very expensive and are not very common in the hobby. Too bad you want to swap them out. Many of these eels sell for up to $45 plus depending on the species and the size. I suspect that they have been breeding in the Val grass and feeding off the numerous baby cichlids being bred in the tank. A few years ago while diving in Lake Tanganyika my wife noticed a pair spawning with cichlids all around eating the eggs. Sorry they are a real pain to catch and I am unaware of any traps available.-Chuck

Questions about Peacock Eel Hi folks!  <Howdy Carol> First of all thank you for a very informative website! I am a constant reader, and have learned much by reading your articles and responses to other people's questions. <Welcome> I have my own questions for you now, regarding a Peacock eel. I raise Mystery Snails and my nursery tanks are nearly overflowing.  <These are great animals... when/where raised "properly"... unfortunately, most all the ones that go "through" normal wholesale channels are either DOA or very close to it...> I would like to relocate some snails to my 55 gal tank which houses a 5" peacock eel. Would this be safe? <Should be... small snails might be eaten, but this Mastacembelid does not eat larger snails by and large... however, worms of all kinds are history> I don't want to create a scenario that is going to result in snail carnage. I have some Sterbai Corys (10) in the tank with the eel. The LFS was adamant about Peacock eels being 'very, very gentle' and no problems at all with snails. However, I don't know if I can trust them as we all know that LFS's are renowned for misinformation. <All must by evaluated by you in the final synthesis> I have read on the Web conflicting information about Peacock eels, some say that they are extremely aggressive and will take small fish (like Corys) when they get large enough to do so. <I have never seen this... and have handled hundreds of Peacocks... other spiny eels that get much larger (e.g. erythrotaenia, the Fire) don't even touch armored cats...> I have also read that Peacocks are very gentle and won't eat anything aside from live worms, perhaps the odd bit of fresh shrimp, and/or ghost shrimp. <This is my opinion> Can you please tell me the truth... would such an eel take mystery snails, or bite off their tentacles? My snails range from babies of a few mm long to full sized adults. I have even contemplated another tank just to house the eel, but I've run out of room for more tanks quite some time ago. (I guess I could rearrange the furniture again though...).  Also, how do Peacock eels do when housed with members of their own species? <Very well... are extremely social animals> I was advised to get a second eel to make mine feel more 'at home'.  Thank you so much for any information you can give me! Sincerely, Carol <Thank you for writing. Bob Fenner> 

Peacock Eel average questions/conflicting answers I just discovered your website and I LOVE IT! I've been a constant freshwater fish fan for years and I have just purchased a peacock eel (Mastacembelus erythrotaenia <<This is a/the Fire... perhaps Macrognathus siamensis? RMF>) and I was just wondering if there was any way to tell the difference between the sexes. Also I have done as much research as I can and I have found so many conflicting reports it makes me dizzy. I just want to make sure I have the basics right so that he/she can live long and happy. For now he's in a 29 gallon (and in about 4 to 5 months to be moved to a 75 gallon) and the temperature goes from 70 (at night) to 75 (in the day). He is in something the pet store called "red sand" but it isn't red and looks like normal sand. The pH sometimes varies from 7.1 to 7.4. He seems to love the sand and only 5 minutes after releasing him he had found a perfect spot to dig and stick his head out. Some of the websites I visited said that they could eat flakes or pellets, is this true? for now he seems happy just to eat bloodworms that come out of this feeder when they are unfrozen. I was thinking (because I know in general spiny eels like live food) to add 1 male guppy and 2 female guppies so that when they mated he could eat the fry. My brother has a soft shelled turtle that he does this with and it seems to work rather well. In a couple of websites they said it would be ok to put him with a knife fish. My knife fish is very friendly and for the short time I had a sting ray in there (babysitting for a friend who's bacteria had all died after his younger brother poured in a bunch of VERY old fish medicine) the knife fish actually made friends with him and would swim just above him and tickle him with his lower fin. These are a lot of questions but I really want him/her to be happy. (I also like to know whether they are male or female so I can name them). >> Your eel should be called "fire eel" by its common name. The peacock spiny eel is another species, that does not have the red lines on its body. If it is a fire eel, it will get to a very large size, that means over three feet long, and he will need a tank large enough to live as he gets older. They do like live food, especially live earth worms. He should be fine with a knife fish. You may want to make sure that your temperature is more stable, best between 74 and 80 degrees Fahrenheit. Good Luck, Oliver

Fire Eels Hello-  I came across a website that had your email address and some information on the fire eel. A friend of mine recently purchased a fire eel and would like to get some more info. Would you happen to know how one goes about determining the sex?? <Not able to do... externally... as far as I'm aware> Also, is it ok to put more than one eel in your aquarium?? <Yes... a docile (though does get large) species toward fishes bigger than mouth-size, including other Mastacembelids. Bob Fenner> She would really appreciate any info you could give on the subject.  Thank you, JB Hampton Striped peacock eel info   3/16/06 Dear Robert, I am new to eel care and have some questions regarding eel behavior.  My eel is approximately 6-8 in long (I'm not sure exactly because he doesn't stay still) and appears to be healthy.  I have only had him a few days and he still looks pretty nervous about his new home. <Typical> I have a 55 gallon aquarium with 1TB aquarium salt for every 5 gal.  I am unsure about this but have read they do ok in brackish aquariums. <To an extent, yes> My main question is that could my 6-8 in eel eat a 3.5 in Senegal bichir or 5 in violet goby? <No, could not>   My bichir is terrified of my eel and the violet goby is MIA at the moment.   <The latter may have "jumped out"... look about on the floor... or be hiding.> Also I am unsure he is getting enough to eat I have tried fresh raw fish, cut Nightcrawlers, and shrimp pellets.   I have heard and read that these are all foods accepted by eels but I am nervous anyway.   <Best to offer some live worms, insect larvae that sink...> would a sort of community feeding spot work? <Mmm, could> None of my other fish are terribly voracious and I was thinking of a watering hole type situation.   If you could help to unravel some of this I would appreciate it. Sincerely, Matt Tompkins <I do hope your livestock all settle-in... they should be compatible... that is, "get along" with another. I would not add any more salt than you mention... and would try black worms, Tubificids for your Mastacembelid eel for now. Bob Fenner>

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>

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