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Cardisoma sp. (likely C. armatum).
Southeast Asia, Indonesia Land Crabs. Soap-Box Crabs for how
they're individually shipped (in plastic soap-dishes closed
with rubber bands) to prevent cannibalism. To eight inches
across... Not a community tank item... Actually not totally
aquatic... if you're lucky, yours will crawl out of the tank
Updated 4/8/18, Ask us a question: Crew@WetWebMedia.com
Brackish INDEX to Articles and FAQs;
Other Specialized Daily FAQs Blogs:
Planted Tanks, Ponds,
Daily Q&A replies/input from the WWM crew:
Monks, Marco Lichtenberger, Eric Russell, Chuck Rambo, Bob
Fenner, are posted here. Moved about, re-organized into individual
Figure 8 puffer, please help! 4/6/18
I would like to start by congratulating you on such a marvelous site, You are my
one stop shop for any fish related question I have!!
<So no pressure then...>
Unfortunately I have stumbled upon a problem that is proving hard to find help
for. I have a figure 8 puffer, alone in a 15 gallon tank. He was bough from a
local fish store about 2 years ago, as a fresh water fish but as you advised, I
gently introduced brackish water.
We are having some building work done in our home, so I needed to move the tank,
so rather than stressing him out by moving him from one tank to another, whilst
doing my water change we decided to move the entire tank, whilst if was only
half full, which went very well, ( although rather heavy!) without any hiccups!
<Can be done this way, yes; but do be careful -- the silicone seals aren't very
resistant to 'twisting' when the tank is moved, so slow, weeping leaks are a
risk when moving a partly filled tank.>
Once moved and the water change completed, in its new location, my puffer was
swimming around happily coming to the front of the tank to greet anyone who
I was so happy with my little fella coping so well with the move that a few days
later I decided to reward him with some live blood worms, as he normally has
frozen, which he guzzled down.
However the next day I noticed that his belly had strange lumps in (and I
apologise for my crudeness) his anus seemed rather noticeably open.
<Can happen if the fish has overeaten and the pressure of food behind the anus
is forcing it open more than usual.>
This is not just the normal big belly after food, but almost 3 small pea size
<Likely just mouthfuls of food; I would not worry if the problem cleared up
within a day or two.>
I have attached pics to try to show them.
<Yes; can see the issue.>
I read up on you site and though that maybe he is constipated, so I added some
aquarium salt to his tank.
<Alongside the marine salt mix? This will achieve nothing. To be clear, it's
Epsom salt (magnesium sulphate) that helps with constipation and bloating, not
common salt (sodium chloride). 1-3 tablespoons per 5 US gallons/20 litres.>
That was 2 days ago now and he doesn't seem to have changed, still 3 large lumps
in his belly and although he isnt eating the food I offer him, He is still
swimming around as normal and coming to say hello every time I walk up to tank.
<Then I would not worry too much. It is common (though bad practice) for
pufferfish to be overfed to the degree they become bloated, and if left a few
days, they will sort themselves out. This isn't natural though, and reflects our
tendency to provide them with a much richer diet than they'd get in the wild.
Epsom salt can help with constipation, as will high-fibre foods such as cooked
peas, or failing these, Spirulina-loaded frozen brine shrimp or live daphnia.>
Do you think it could be caused by the stress of the move or is it more lightly
constipation? If so how long should it take for the salt to..... relieve him?!
<Epsom salt will work quickly; a few hours.>
Should I just keep adding the aquarium salt to the water once a week whilst I do
my water changes until the lumps go? Or is there something else I should try?
<There is NO need to add extra aquarium salt on top of the marine salt mix. Will
achieve nothing, and will be raising the salinity somewhat, which may be harmful
to any plants in the tank. The puffer won't care, of course!>
As I said he's not eating now either, how long will he be able to survive
<An adult fish this size should be able to go 6-8 weeks without food.>
Is there a chance it could be internal parasites? if so is there a product you
would recommend in the UK, Im struggling to find one on the UK market.
<I don't think that's the issue here.>
I am sorry to bombard you with questions, but we have become very fond of the
little fella, so any help you could offer would be much appreciated,
Other info I thought you might want to know is, diet of frozen bloodworms,
snails and cockles in shells,
Ph is 7.5
nitrate between 0 and 2.5 ( it wasn't white but a slight pink tone to it)
water salinity 1.005
water temp 24.5
Many thanks and Kindest Wishes,
<Hope this helps. I would not be concerned about internal parasites or worms
unless this persisted for more than a few days. Two days' bloating sounds like
constipation, and can be treated without anything more expensive than Epsom
salt, which you may well have at home anyways, and checking online, apparently
£2.49 for a kilo at Boots drugstore! Way more than you'll need, but nice in a
hot bath, too. Cheers, Neale.>
Switching from Freshwater to Brackish
Well, my latest sick Oscar has recovered (thank you Neale) and left this
afternoon for his new home.
So now I have an open 72 gallon tank that I would like to change
from freshwater to brackish for a dragon goby.
<Interesting choice. These big, quite friendly fish make good pets. They
are a little demanding in some ways, needing brackish water for example,
but in other regards extremely tough. Their biology in the wild is
fascinating. They live in tidal rivers where they are sometimes forced
to survive for hours in a wet burrow when the tide has gone out! So
unusually among marine fish they are able to breathe air. Many species
in their group lack eyes, and even the ones with eyes have such tiny
little eyes it's hard to imagine they see much. In the wild about half
their diet is reported to be algae and organic detritus, so needless to
say they're not fussy feeders, but their large size does mean they need
quite a bit of food.
Besides algae wafers and the like, they readily consume bloodworms,
brine shrimps, and other small invertebrates, but even the adults (which
can measure over 40 cm/16 inches) very rarely take live fish, even Guppy
fry, unless absolutely starving.>
I've done my research and spoke to the company I would be getting the
goby from and they say the fish (about 4 inches) is currently a
<Yes, often the case that they're shipped that way, but trust me, they
all come from estuaries and tidal mudflats. They are highly specialised
fish, rather like Mudskippers, that only 'make sense' in very specific
So my thinking is that I would get the fish, put it in my currently
freshwater 72 gallon tank, and slowly acclimate both the fish and the
tank to brackish water.
<That would work fine. You might want to change the decor of the tank
though, which you can do with the filter running. Depending on the
circumstances, you might want to remove any live plants (these are
unlikely to do well in brackish water) and replace gravel with smooth
silica sand (which these gobies like to burrow into). Rocks should be
smooth water worn cobbles to avoid scratching the goby, and the use of
hollow tube-shaped ornaments will provide useful hiding places. These
fish are rather shy initially, so shelter is important.>
But I want to be very careful doing this as I use RO/DI water with
Equilibrium and baking soda for a healthy pH/kH which has been working
<Unless your tap water has very high nitrates, there's really no
advantage to using RO water instead. Because you're adding minerals to
the tap water, and these fish demand high levels of dissolved minerals,
tap water rarely
presents any serious problems for brackish water fish. The exception is
high nitrate, which can cause algae problems. Otherwise things like
ammonia and copper in the water can be treated in the traditional way,
with a good water conditioner.>
I plan to use Instant Ocean to make the brackish water.
<A fine choice. But because brackish water fish are less demanding than
marines in terms of pH and mineral, even cheap generic sea salt brands
can be fine, and save you a few bucks over the years.>
I have sent e-mails to both Seachem and Instant Ocean telling them of my
plan and asking these same questions: 1) I normally do 20 - 25% water
changes weekly, Can I slowly acclimate the tank through my weekly water
changes or should I do it more quickly or more slowly than once a week?
<I would go much more slowly than this. Assuming the fish is in
freshwater now, I'd introduce the fish, and then immediately do a 25%
water change with water that has a salinity of SG 1.004-1.005. The
resulting salinity in
the tank should be around SG 1.001. That's fine for the first day or
I'd then do something similar, a 25% water change with SG 1.004-1.005
water, every other day. Crucially, this would result in the salinity
going up gently over the course of a week or so, allowing the filter
bacteria to adapt. Nobody really knows if marine aquarium bacteria,
brackish water bacteria, and freshwater bacteria are all the same things
or different species, so it's best to assume the latter, and allow the
tank to do a 'mini cycle' over the course of a few weeks. Once at SG
1.004-1.005, leave the tank alone for a couple of weeks at least. This
should be fine for the goby, and if he's feeding happily, there's no
need to raise the salinity further for a good while yet.>
2) will the Instant Ocean in the replacement water cause drastic changes
in pH/kH as it mixes with the water currently in the tank that contains
Equilibrium and baking soda or are there any other potential
between Equilibrium/baking soda/Instant Ocean that I should be aware of?
<There will be little difference in the pH before adding the salt and
afterwards, though it might go up a tiny bit. The hardness (both general
and carbonate) should go up a little too. But not enough to harm the
Similarly, while these changes will have an effect on your filter
bacteria, if you go slow, it won't be noticeable. Normally, there's no
need to add Equilibrium and baking soda to tanks with marine salt mix
marine salt mix essentially includes those two chemicals in its
3) in my research I came across a random post in a saltwater forum that
Instant Ocean is not sufficient to keep a healthy kH when used with
RO/DI water (this was a saltwater forum, not brackish) and that I would
use Seachem Alkaline buffer for that purpose. Would this be accurate for
a brackish tank?
<This is a debatable point, but worth thinking about. Normally, marine
salt mixes contain alkaline chemicals that buffer against pH changes, so
you shouldn't have to add anything extra, such as baking soda or a
alkaline buffer. But if you find the pH drops too quickly between water
changes, then you might need to do so. If we recall that pH drops are
caused by decaying organic matter in the tank, then if we have a
spacious tank that's well maintained, there's no reason to anticipate a
rapid drop in pH. Make sense? Bear in mind that these fish come from
highly variable habitats, and are MUCH less fussy about pH than their
marine cousins. So provided the pH doesn't go below, say, pH 7.5, you're
probably fine without adding anything beyond the marine salt mix.>
4) The information I've found said that the best SG for a dragon goby is
1.006, does that sound right to you?
<Anything between freshwater and full marine would be experienced in the
wild, so yes, 1.006 is fine. As noted earlier, I'd aim for 1.004-1.005
initially, simply to allow the bacteria in the filter to adapt. Once you
go above 1.005 you seem to get a mini-cycle kicking in, so I'd wait for
the goby to be settled in, and only change the salinity up if you feel
the need, and even then, in little steps through weekly water changes to
allow the filter to adapt. What you don't want is an ammonia spike. To
be fair, these fish actually handle high ammonia levels quite well,
being forced to live in wet burrows at times, but this isn't something
you want to deliberately cause for obvious reasons! Furthermore, your
final salinity might depend on your chosen tankmates. Many people keep
these gobies with
livebearers, whether Guppies or Mollies, since these 'dither fish' help
the goby feel more settled and secure, and add some colour and activity
to a tank that can sometimes seem a bit Spartan. Mollies are also good
I have buckets spread all over my bathroom and I'm going to start
testing as soon as I pick up some Instant Ocean tomorrow, but any
guidance you can provide would be greatly appreciated. I'd love to have
this fish, but I
have to be sure I can take care of it well before I jump in. Thank you!
<Hope this helps. These fish are genuinely not difficult to keep. But do
make sure they can't jump out: like most eel-shaped fish, this can be
risk if the tank has any large holes in the hood. Cheers, Neale.>
Re: Switching from Freshwater to Brackish
Thank you so much for all the information and guidance.
You've made getting this fish fun instead of stressful now that I have a
Attached is a picture of his/her tank.
It's a 72 gallon with a Fluval 405 canister filter on it.
<A good filter.>
Tank temperature is 78 degrees.
The substrate is pool filter sand and all the plants are plastic.
<Both good choices. Algae control may be a problem without live plants
though. Various approaches here, from the use of brackish water snails
(such as Batman and Spiny Nerite snails, Clithon corona, Clithon
sowerbyana, and Neripteron auriculata; also some US native species can
work too, e.g., Neritina reclivata) through to careful control of
lighting duration (4hrs on, 2hrs off, 4 hrs on) and nitrate control
(minimal food in, regular water changes out). Still, if you get the tank
right, with a good strong current in particular to keep down blue-green
algae, the only pest algae will be diatoms, and they're easily
controlled with Nerites.>
It's been up and cycled for a little over a year. It has a plastic egg
crate top that I cut specifically to fit this tank that did very well
keeping my Rope Fish in there when they had that tank.
It has a very snug fit to, so if the fish push on it, they won't be able
to move it. That mass of plastic plants in the center is actually
covering 4 - 2 inch pvc pipes, one on top of the other and fastened with
zip ties. One tube is 24 inches, the next up is 18, next is 12, and the
top tube is 6 inches. I know these fish get to be about 16 inches long,
but I don't know what to expect in terms of diameter, but I'm prepared
to make him/her a new "fish condo" out of 4 inch pvc if necessary.
<Understood. Juveniles should fit happily in the tubes you already have,
and under aquarium conditions they're unlikely to get quite so big as in
the wild. I think you're going to be fine for a couple years at least,
and should you need to upgrade, that shouldn't be hard to do. Any
ceramic ornament big enough for an adult Plec will be fine for an adult
Also, I have cut holes at 4 inch intervals along the tubes, about 1 inch
in diameter, on both sides to ensure water movement within the tube so
it doesn't stagnate. I can't find anything online that says these fish
like a strong current, so I do not have a powerhead in the tank.
<They do like strong currents, as do most gobies, but I'd be using a
strong current more to avoid blue-green algae than for the fish. Still
corners tend to be where blue-green algae starts off, and once in your
tank, it's a real pain to eliminate.>
I use RO/DI water for all the tanks because I'm on a well in a very
rural area and my tap water has 1 ppm of ammonia in it AND human remains
(probably wouldn't bother the fish, but it gives me the heebie-jeebies!)
<Understood, and yes, the fish couldn't care less. Ammonia will be
neutralised by a good quality water conditioner, and as for the human
remains, "parts-is-parts" so far as the biological filter goes. The
reason I often advocate against using RO or DI water is a cost issue:
people are more likely to do more frequent water changes if they can use
the cheap water from the tap. If they need to be spending money on RO
membranes, carbon filters, and all the rest of it, they're more likely
to minimise the use of new water for doing water changes. Ultimately
it's a balance. For sure, RO water is best, but 5 litres of tap water
trumps 1 litre of RO when it comes to water changes! Make sense?>
I actually have never tested the tap water for nitrite or nitrate.
<Neither are critical factors here, but if your nitrate is very high,
say, more than 20 mg/l, then algae problems are more of a risk, and you
should take precautions as mentioned above.>
So I ordered the fish and he should arrive Friday. I have to have him
delivered to the fish store where I get my supplies because UPS doesn't
come out to my house. When I pick up the fish, I'll pick up the Instant
Ocean and the store owner is going to loan me a refractometer until I
can afford to buy my own.
<Refractometers are nice an' all, but for brackish they're overkill. At
25 C/77 F, 1.005 water is about 8.9 gram marine salt mix per litre (1.18
oz per US gallon) and can be made up using kitchen scales using these
according to however much water your bucket holds. For example, a
5-gallon bucket would need 5 x 1.18 = 5.9 oz marine salt mix. Once
you've done that, and it's all dissolved nicely, a plain vanilla
hydrometer can be used to
check the specific gravity, and if the hydrometer is 'off' a point or
two, just make a note of that, perhaps by putting a permanent marker
line on the scale, and remember that's the level you want, not the
number on the scale.
Refractometers are fiddly and need calibrating, and don't, in
themselves, mean you're getting more accurate readings just because
they're more precise (accuracy and precision being completely different
Thank you for the suggestion about the Mollies for dither fish, but how
many should I get without pushing the stocking limits of this tank?
<Oh, for a tank this size you could safely start with 6-8 specimens and
let nature take its course. I'd get a single variety so that you can
share the offspring with local pet stores, Mollies being popular fish.
If you were feeling ambitious, you could get one of the two Sailfin
Molly species, as these occur alongside the Violet Goby in the wild, so
that'd been very authentic. Giant Sailfin Mollies in particular are
expensive and difficult to breed in freshwater, but in a brackish tank
will breed readily, adding value to your set-up. Alternatively, there
are things like Micropoecilia picta and Micropoecilia parae that are
very beautiful, difficult to keep in freshwater, and rare enough that
any offspring produced would be easily sold on. As their name suggests,
Micropoecilia are small, so you'd easily be able to keep a large group
of them in a tank this size. As we've discussed, Violet Gobies generally
ignore small fish, so you should be safe, but you might try out a few
Micropoecilia first before buying a whole
So as you read this, can you think of anything I've missed?
<See above! Cheers, Neale.>
Re: Switching from Freshwater to Brackish
Thank you again! Have a wonderful day!
<Off to the pub to meet a couple of friends, so that should be nice; my toddler
deciding to vomit all over the sofa, less of a highlight. Cheers, Neale.>
Re: Switching from Freshwater to Brackish 4/6/18
P.S. Per your suggestion, I just put a smaller powerhead in the tank. When I
moved the BGK and the Ropefish to my 125 gallon, I had to get them a bigger
powerhead. So I put their old one back in the 72. I don't remember the gph, but
it worked well for the BGK when it was in the 72 gallon.
<Should work fine. To combat blue-green algae, what you want is the water
*across the substrate* to be moving. So position the powerhead accordingly.>
Also, you mentioned the goby will need algae wafers for a balanced diet.
Will this fish also enjoy cucumber, zucchini, and peas like my Bristlenose
<Yes indeed. Violet Gobies are omnivorous, and very adaptable in captivity, but
all reports on wild specimens confirm that their stomachs are more than
half-filled with algae and organic detritus. In other words, very similar
to Plecs, and a similar diet should work nicely. Indeed, have odd little teeth
in their mouths that can be used to scrape rocks, and some aquarists have seen
them feed this way in their tanks. Cheers, Neale.>
Re: Switching from Freshwater to Brackish 4/6/18
Oh, I'm sorry about your sofa! But at least you have a little while before the
baby starts asking for the car keys!
Enjoy your day, and thank you again!
<Most welcome. Neale.>
Re: Figure 8 puffer, please help! 4/7/18
Thank you so much for your quick reply!! I was unaware that the aquarium salt
wasn't Epsom salt!!
<Oh! Well, glad to help.>
I did ask in my local fish store and they told me that marine salt ( that I use
to make the water brackish) was different to the aquarium salt,
<It is. Aquarium salt is basically sodium chloride, perhaps with some other bits
and bobs added, but really not much different to the sea salt you'd buy at the
supermarket. Marine aquarium salt mix, on the other hand, is mostly sodium
chloride, but also a whole slew of other minerals, like calcium carbonate, used
to buffer against pH changes. It isn't "dehydrated seawater" but rather
something with the properties of seawater in terms of salinity, but a much
higher ability to resist pH changes.>
so I assumed that aquarium salt was another "brand" of Epsom salt..... I know
Not a problem, thank you for clearing that up, and off to Boots I go!!!
Thank you again for your help,
You really are the fish whisperer!!!
<And thank you for the very kind words, Neale.>
OMG! He's Eating! Dragon Goby
Hi Crew! Hi Neale!
Just so excited I had to give you an update - the Goby has barely been in his
new home for 24 hours and he's out in the middle of the day, with the tank light
on (it does have a diffuser) and he's eating. With everything I read about this
species on the Internet, I was expecting to have a problem getting him to eat,
so this is better than I dreamed possible!
<Certainly sounds promising.>
When I got him home yesterday, he went right to the bottom of the tank and just
stayed there for about 20 minutes and then vanished into all the great hiding
spaces I made for him. So I did as you suggested and did a 25% water change and
mixing the replacement water to SG 1.004. As you predicted, that brought the
whole SG of the tank up to 1.001.
<Sounds about right.>
Then I just left the lights off and let him rest for the remainder of the day.
Then last night, just before lights out, I made him a little stew of mostly
nori, but spiced up with a little bit of chopped bloodworms, Tubifex (Hikari)
worms, and some brine shrimp - fed that and turned out all the lights in the
<Do be careful not to mince particles of food too small -- these end up in the
filter and decay, doing the water quality no favours. Better to have fragments
big enough you can remove any surplus easily if you need to.>
Didn't see him this morning, but didn't really expect to, so I just gave him a
little bit more "stew" and went about my day. But just ten minutes ago I saw him
out swimming around the tank until he found a pretty good sized piece of nori
and the he just sat there eating away till it was gone and swam off in search of
more. So here's my happy question; my aquarium supply store sells sheets of
algae for marine fish. Should I get him some of that? Is it healthier for him?
Or should I stick with the nori because he's eating it?
<The algae sheets sold in pet stores for marine aquaria is usually exactly the
same stuff as the nori sheets sold in Asian food markets. Use either; use both;
whatever suits your budget and/or convenience best!>
<Indeed! Cheers, Neale.>
Re: OMG! He's Eating! 4/8/17
<Most welcome, Neale.>
More observations of Uropterygius Micropterus and other morays in my
brackish aquarium 2/3/18
Hello Marco, Neale and all you good people in WetWebMedia,
As I promised. here are my latest observations of my FW/BW morays.
Both Uropterygius micropterus are doing fine, they seems to be adapting well in
my aquarium. I am fluctuating the salinity between 1.006 sg to 1.009 sg, to
simulate a semi-brackish river not so far from the estuarium.
The U. Micropterus shows normal behavior, no signs of stress, they even got
brave enough to get out of their hiding spots every now and then to chase feeder
guppies all the way to the surface. They won't run away from
my fingers when I am doing aquarium maintenance. Both eels have their own
favorite hiding spot, the older one likes to hide under a clamshell, while the
newer one likes to hang out with other morays in a pipe.
One behavior in particular that I observed with the U. micropterus, is that they
often opened their jaw in a menacing kind of way, keep it open for 10-15
seconds, then go back to normal breathing. This I never observed on my other
<Sounds like typical threat display of morays.>
The smallest E. rhodochilus seems to hang out with the U. micropterus a lot,
perhaps due to similar size. I once seen them swimming together side by side
with the same rhythm and same speed. I am still not able to persuade the
smallest E. rhodochilus to eat fro3en food. I observed that when the bigger E. rhodochiluses are eating frozen food, the smallest one seems to be keeping
distance. Perhaps there is a "caste" system among eels based on size?
<It's much easier to train them to take frozen food, when there are no other
The other E. rhodochilus are getting fatter after I regularly fed them with
thawed frozen shrimps & squids, now they no longer actively chase guppies and
live shrimps, and they even backed off from larger Macrobrachium shrimps if
those shrimps are fighting back. Those shrimps has grown bigger now, and even
the G. polyuranodon are not frightening to those large shrimps anymore. I was
thinking of evicting those shrimps that has grown too large, but then I decided
to keep them, as cleaning crew. Anyway, are they capable of hurting the morays
in any way?
<At their current size? A healthy moray? I doubt it.>
How big will those Macrobrachium shrimps grow?
<Depends on the species. Typically around 7-9 cm, but there are really large
ones such as Macrobrachium rosenbergii, which can reach 30 cm and at this size
may pose a threat to your small eels in the limited space of an
Speaking of my G. polyuranodon, it seems to have the most diverse diet of them
all: it will take feeder guppies, small bits of frozen shrimps and squids (it's
not interested in big bits), and even bloodworms which I intended for feeding
the guppies and shrimps. It is also the most active of the morays there,
spending equal time between hanging out in its pipe and swimming around, even on
the surface, terrorizing the guppies. It will also making occasional attempts
every now and then to jump out of the water, like dolphins. That's why I keep my
aquarium tightly covered.
<Usually there is a reason when morays try to leave a tank. Happens mostly when
they are new, when the water quality is not sufficient, when the tank is too
full, when there are larger predators or when there are not enough
or sufficient hiding spots. Many also seem to be quite curious and just
investigate their environment above the water level.>
Interestingly, the E. rhodochilus never, ever made any attempt to jump out of
the water, unlike the G. polyuranodon.
<Guess they like it better there.>
Even the U. micropterus made some attempts. Seems like it's a normal behavior
among piscivore morays, but not so normal among Echidnas?
<No certainly not a genus thing. Happens with Echidna species, too.>
Well, that concludes my report for now. Will post more info here soon.
<Thanks for the report, Ben. Very interesting indeed!>
Thank you and have a nice day!
Best Regards, Ben
Re: more observations of Uropterygius micropterus and other morays in
my brackish aquarium 2/25/18
Good evening, Marco, Neale, and all you splendid people in WetWebMedia,
<Welcome back, Ben!>
Allow me to post an interesting observation.
Lately both of my Uropterygius has invented a new way of hunting. They will
climb my filter and remain on top, their bodies outside water, but with their
heads underwater. Then they will *chomp* unsuspecting guppies that comes close.
I noticed that they started this behavior when I reduced my water level to be a
bit lower than before. When they're not on top of the filter, they usually lie
under the filter, with their heads up (making a "J" shape),
intently watching the guppies overhead. They are willing to take frozen shrimps,
but they seems to have their hunting instinct still intact, unlike my other
morays, who has begin to prefer frozen meal than hunting live guppies and
shrimps. (In fact my smallest E. rhodochilus now has begin to eat frozen meal as
well, though in smaller portions).
<Very good. As I said, it might take a while, but all morays can be trained to
The kind of hunting method that my U. micropteruses now used, is actually not so
alien to me,
<Never heard of it either, although I had some moray eel specimens in the past,
which loved to live inside a skimmer.>
I think my Monopterus albus (now sold) also used the same hunting tactics when
it was smaller.
What surprised me is the fact that U. micropterus, despite being morays, are not
afraid to temporarily leave the water to hunt for food. Before, I thought this
kind of behavior only apply to M. albus or other kinds of swamp eels.
<There are actually quite a number of reports of moray eels leaving the water in
the wild, mostly to hunt crabs. G. pictus and also E. nebulosa e.g. have been
reported to do that, but I have not heard of any morays lurking for fishes while
being outside of the water, especially no Uropterygius.>
Too bad they are not popular yet as pets, otherwise I'd love to hear from other
U. micropterus keepers. They are not as easily found as other morays commonly
kept as pets (such as G. favagineus, E. nebulosa, G. polyuranodon
etc), but still very interesting and challenging all the same.
<They sound like a very interesting species.>
Well, that's all for now, have a wonderful day!
Best Regards, Ben
<Thanks for your report. Have a nice weekend. Marco.>
Re: more observations of Uropterygius Micropterus and other
morays in my brackish aquarium 2/28/18
Hello Marco, Neale, and all you excellent people in WetWebMedia,
Thank you for your kind words & input. So it's true that morays, like
swamp eels, can actually leave the water temporarily to chase its prey.
This actually makes sense for Uropterygius especially the beach
population, if they got stranded in small pools, maybe they will use
their ability to get out of the water temporarily, to move overland from
small pools back to the sea.
This email is my last observation for the two Uropterygius micropteruses
that I had. I returned them to Mr. Eko today.
Now that we have established that U. micropterus can be a good pet in a
brackish water aquarium, I hope he will continue to spread the news to
all other fish lovers and procurers, with a message "don't throw those
ugly, snake looking eels back to the water, they can be good pets!". The
reason I returned them to him, are two folds, Firstly because I think my
observation is done, and Secondly, because I noticed that those
snake-eels, are much more sluggish and too docile compared to the larger
morays, thus are best kept on a species tank.
Just a few days ago I recorded a scene where my largest Echidna
rhodochilus literally snagged U. micropterus's lunch right under its
nose, while the U. micropterus still blindly trying to figure out where
its food were. This
tells us that, while inter-species aggressions amongst these FW/BW
morays are not observed, the smaller morays are clearly outcompeted by
their faster cousins, and thus are in danger of starvation. Notice that
U. micropterus need to sniff
around a lot to find food, while E. rhodochilus seemed to find food
<Interesting. Don't seem to rely on their eyes too much. Also breathing
Therefore, we can assume that it's best to keep U. micropterus in its
own species tank, and away from faster species.
<Actually I think that's best for many morays.>
Since I have no spare space for another aquarium, I returned the eels to
Mr. Eko, who now keeps them in a species-only aquarium. I will off
course continue to post here about my remaining eels (G. polyuranodon
and E. rhodochilus), and also about my future eels if I can get them. I
am thinking G. tile or G. meleagris or E. leucotaenia if I could find
them. Fishbase said they're capable of living in BW and FW, and that
their range extends to my country. So, there is hope.
Well, thank you for your kind attention & input!
<Thank you for your work and reports. You produced probably the first
reports on U. micropterus as an aquarium fish. Now your results are
available world wide for others to learn and continue.>
Best Regards, Ben Haryo
<Cheers and all the best. Marco.>
Re: more observations of Uropterygius Micropterus and other morays in
my brackish aquarium 3/3/18
Good day dear Marco, Neale & all you splendid people at WetWebMedia
Thank you for your kind words. I will certainly post interesting moray-related
things every now and then, especially concerning those species which are
frequently encountered in our rivers.
One last question about our last videoclip (here
https://www.youtube.com/watch?v=EBt7eGzvXCQ ) At the beginning of the clip,
you see a rather large guppy swimming above the U. micropterus. We call it "Cere
Payau", I am not sure what is its Latin name, so what it is?
<Are you sure this is a Guppy? Could also be some Xiphophorus sp. female.>
That guppy has grown a lot from since I put them in the aquarium. I think it is
now too big for all my morays. But it started as very small fish. Now that my
morays all has learned to take frozen food, should I evict those guppies?
<You can evict them if you think the tank is too busy. At some point they still
might become prey. G. polyuranodon do get quite big (at least two feet, probably
more). The large one I once kept would have eaten those livebearers.>
Thank you & have a nice day!
<Will forward this to Neale, who is an expert on livebearers. Cheers, Marco.>
Re: more observations of Uropterygius Micropterus and other morays in my
brackish aquarium. 3/3/18
<<The large Poeciliid would appear to be a female Molly of some sort. These are
well established in Southeast Asia, including brackish and littoral marine
environments. Mollies are distinctive in the way their jaws work,
being rather mobile and well adapted for scraping algae. They are facultative
air-breathers will also sometimes gulp air at the surface. So watch for that
behaviour! I've kept Mollies with a wide range of brackish water fish, and while
they are definitely "food fish" for piscivores, they are quite bold and even
aggressive, and hold their own well alongside anything not overtly lethal!
Re: more observations of Uropterygius Micropterus and other morays in
my brackish aquarium
Hello Marco, hello Neale and all you good people in WetWebMedia,
Indeed dear Neale, those mollies, once fully grown, are aggressive and
courageous. Have a look at this clip:
<There's a fine line between 'courageous' and 'stupid', it has to be said...>
You see that my largest Echidna Rhodochilus (Mr. Emerson) has no problem barging
through smaller fish and got his share. However, my smaller Gymnothorax
Polyuranodon seems to gave up on its food when the big courageous molly were so
determined to eat it.
Maybe when the G. Poly has grown bigger, the molly will be lunch :D
<Could well be; I would expect it to disappear during the night, because that is
when Morays typically hunt smaller fish.>
But for now, molly seems to hold its own turf against smaller morays. Are big
mollies always this courageous?
Well, that would be all for now, thank you for watching!
Large red scat 1/26/18
our red scat ZZ is quite large and is about 9 years old in the last few days he
has developed a lump that looks like a pimple, part way along his spine just
below his spikes and he may have another one coming up a bit further along his
spine I have attached a picture for you can you tell me what it is and how to
treat him he is such a great fish we don't want anything to happen to him.
eagerly awaiting an answer
<Have encountered such pimples on wild and captive scats; and consider that they
are manifestations of point/injuries rather than pathogenic evidence. Hence, I
would not treat the symptoms per se, but just do your best to maintain good
conditions. Steady, optimized water quality and nutrition.
The spot/s will go away of their own accord in a few weeks. Bob Fenner>
Re: Brackish moray ID 1/4/17
Allow me to continue our discussion,
I am thinking about other possible moray species that matches my eel,
which are not Echidnas nor Gymnothorax.
In Fishforums.net a poster listed some species of morays that enters
brackish & freshwater (I think this was quoted from WetWebMedia ;) One
of the species mentioned, Uropterygius micropterus, is interesting,
because when I see this picture here:
<Not sure this is Uropterygius micropterus, but it's possible. Too bad
the dorsal fin is not visible on the picture. Uropterygius micropterus
has a light brown background color with a net of darker lines (see
Gymnothorax richardsonii has a more greenish color with a dendritic
pattern. All Uropterygius spp. have a low dorsal fin limited to the area
of the tail, while Gymnothorax spp. and Echidna spp. have a higher
dorsal fin that starts behind and above the gill opening. The genera can
easily be told apart with the eel in front of you by this character.>
Some of Mr. Eko's eels which he keep in his other brackish tank has the
same patterns on the body with the Uropterygius Micropterus in the
Chinese link above, though the coloration are different, that eel in the
above are more dark brown, while Mr. Eko's eels are more grey-ish brown
(except the one he gave me, it is green-ish brown).
<Compare to G. richardsonii, especially have a look where the dorsal fin
All of his small (<30 cm) eels he said were caught in brackish river,
while the larger marine ones were from coral reefs around small islands.
Price differences also reflect this, the colorful fully-marine morays
costs a lot
more than the small brackish ones.
BTW, the small eel just ate a piece of thawed frozen shrimp. Interesting
how fast it adapts with my aquarium, just a few days and it already ate
frozen meal (smeared with garlic, thank you for your advice!), while my
smallest E. rhodochilus still refuse anything else than live meal, even
after living here for months!
Well, that concludes my observation today. Thank you for your kind
attention & have a nice day!
<Have a nice day, too.>
Best Regards, Ben
Re: Brackish moray ID 1/11/18
Warm greetings from Indonesia. How's Germany today?
<Warmest winter I remember.>
I observed the eel and see no visible dorsal fin that starts above the
gill opening. So there is a possibility that this is an Uropterygius eel
instead of a G. richardsonii or E. rhodochilus?
<If you don't see said dorsal fin on the eel in question, but you are
able to see it on your Echidnas, the mystery moray likely belongs to the
genus Uropterygius (Anarchias would be another option).>
<Sorry Ben, I can't make out any detail in the vid, it's too dark and
blurry. You should use some additional light source when taking pictures
Thank you and Best Regards,
<Have a nice day.>
Re: Brackish moray ID 1/12/18
Nice to hear that your winter is warm, I hope this is good for your
<I don't think they care. It's the same temperature in the house and
their tanks all year round.>
Sorry for the bad quality of the film. I hope to borrow a better camera
later, to take a better picture of my eel, or a cell phone with a strong
<This would be good. Maybe we can get a proper ID instead of just
In any case, if my eel is actually an Uropterygius micropterus as I
assumed, it is already 20cm maybe more, so I guess it's near adult (not
baby eel anymore), as maximum length of this species is 30cm (according
So, if it's really U. micropterus, then we confirm what Fishbase said is
correct (that it is both brackish and marine). It also seems to be happy
in its 1.008 sg aquarium, and are very docile in temperament, it is very
friendly with the E. rhodochilus and G. polyuranodon, no aggression
<Good to hear.>
When I am back to Sumenep, I'll ask Mr. Eko in which part of the river
he captured them: Was it at the river mouth, or further inland, did he
used a submerged trap or did he picked them up in shallow waters. This
way we could have some more info about the habitat of the eel.
<That's a good idea. Most of such useful information is lost with
export, it's great you are close to the source.>
Too bad this species is not so common as pets, as I think this eel could
be one of the easier ones to keep. It is not as pretty as E.
rhodochilus, G. polyuranodon or G. tile, but it is not so hard to feed
and not so shy, mine seems to spend almost as much time swimming outside
the pipes as waiting inside. It also does not run away from my hands
when I am cleaning the aquarium, interesting eh?
<Yes, especially since Uropterygius species in general are reported to
spend most of their lives hidden in rocks and mud, but to be honest: not
much is known about the behavior of members of this genus at all.>
Well, thank you and have a nice day!
Best Regards, Ben
Re: Brackish moray ID 1/17/18
Good evening Marco,
<Good morning Ben.>
Greetings from Indonesia!
I am aware that there are not much information about fresh and brackish
water morays, so indeed, as an eel-enthusiast who lives close to the
source, I'll share whatever information that I can gather from around
<Kudos to you.>
As for our mystery eel, I visited Mr. Eko this afternoon, and asked him
a few questions about the eel. His answers are as follows:
1. The mystery eels that he has, were captured in the river in Java, a
bit farther from the river mouth (estuarium), but he said this species
are also known to inhabit not only on the river, but also the area
around the river mouth and the beach. So, they can be found in both full
saltwater and light brackish. They are from shallow waters, usually
found in sandy beaches hiding in broken corals or under clamshells, or
in the soft mud of the rivers.
2. They are known to hunt crabs and shrimps on the shallow waters of the
beach and rivers. They can burrow their bodies in both soft sand and
mud, but they are more active in swimming around, than other types of
morays which spent much of their time burrowing or hiding. They could
hunt during the day or during the night as they please.
3. These eels were usually not captured by fishing hook, but by
4. They are not territorial, plenty of them can be found together in a
small area, often bunched together under a clamshell or a rock, like
So I thanked Mr. Eko for his info, and he promised to inform me if there
are any other strange eels he captured or obtained. Before I left, he
offered me to buy a pike conger baby at discount, as apparently he has
one left. He told me that the pike conger were captured in the same area
where they captured the mystery eel. But I declined (pike congers are
known to be aggressive and has sharp teeth), and instead I bought
another mystery eel from him.
So now I have two of these "mystery eels", I hope they will be happy in
my aquarium. Mr. Eko took pictures of the conger and the second mystery
eel, I attached it here. His shop is not as dark as my kitchen, so maybe
these pictures are better for ID ing the mystery eel?
<Yes, much better. Can't see details of the head, but at least the body
coloration is visible. It's definitely no G. richardsonii, G. tile, E.
rhodochilus, G. polyuranodon. The coloration of the body matches
Uropterygius micropterus quite well, so this ID is probably right. The
ecology you describe above also concurs with what is known about this
species. Only that it seems to live so openly is something I had not
expected from a Uropterygius species. I think this eel can be added to
the list of moray species in captive care.>
That concludes my e-mail for now, I will share to you more from my
research when I get new information.
Warm Regards, Ben
a bunch of morays in a bucket 12/28/17
Hello Neale, hello Marco, hello all,
Warm greetings from Indonesia to all you amazing people at WetWebMedia.
So, I visited an ornamental fish procurer, the one who actually captured the
fishes. I asked for fresh or brackish water morays. He showed me a bucket full
of eels that he captured several days ago from a river in the
north of Jakarta, not far from the estuarium river mouth.
Here are the pictures of the eels.
So, which one is Gymnothorax Tile? I can recognize one tiny Echidna Nebulosa,
but the rest of them I have no clue. I am not even sure that they are all
morays. The guy who captured them all made no distinctions, all of those eels
are "Belut Muara" to him (Belut Muara = eels being caught in brackish water).
<The pictures show too little detail for a proper ID. Would need to clearly see
the heads of most of the eels. As you already know there is E. nebulosa and
probably G. richardsonii. There might also be one (the grey eel with tiny spots)
or two Gymnothorax pictus, which are easily IDd by the dark spots in their eyes.
However, I cannot see the eyes on the pictures.
Gymnothorax tile are grey to brown with yellow the golden speckles. The older
the eel, the less golden speckles. See here for some pictures:
Young G. tile look like
The pictures you mailed of Mr. Septian's eels also show some G. tile and one
potential G. pictus. >
Thank you & have a wonderful day!
Best Regards, Ben Haryo
<Hope this helps. Marco.>
Brackish moray ID (file size fixed) 12/30/17
Hello Bob, Neale, Marco, and all my WetWebMedia friends, a good Friday for all
(Dear Bob, sorry for the large files, my bad. I have re-sized the file and
re-send the message. I hope this time it's in the correct size. Sorry for the
Marco, thank you for your kind explanation. Brackish water is fascinating, isn't
it? I like the concept of brackish and near-freshwater estuarium as nursery
ground for various juvenile marine moray species, so they could get the
nutrients from freshwater and cover to hide from marine predators. Our estuarine
waters are indeed dark and muddy in many places, unlike the clear bright waters
of the coral reefs just a few kilometers at the open shore.
I have made plans in the future to visit some of those estuaries & rivers in
North Java and in Yogyakarta & record their salinity levels & record the tales
about morays from local fish catchers.
<Nice. If possible compare the salinity at the bottom of the estuary with the
surface. Can be quite different.>
I will keep you informed.
I am also interested in marine aquarium, but maybe later when I have more space.
Space is a problem for me as I cannot find place in my house for another
aquarium. I often found myself donating my pet fishes to other friends, not long
ago I donated my Anguilla bicolor to a friend who has a larger aquarium, as it
has grown almost to 1 meter in length & looking very stressed & cramped in mine.
It had spent almost 3 years in my aquarium.
Currently I am also looking for a new home for my Monopterus albus, it has grown
to 70 centimeter and has shown signs of stress, before it's very active, now it
became lethargic, often perched itself on top of the filter (glad my aquarium is
covered!) or bury its head on the sand (glad the bottom of my aquarium is sandy,
not gravels!). I have
donated other fishes in the past as well.
<You seem to like all eels, not only morays. As far as I know, M. albus does
travel into brackish waters, but prefers freshwater in the long care (and
Well, today I went to my hangout at Sumenep, where fish lovers hang around.
I visit my friend Mr. Eko, a specialist of brackish water fishes. Not only
catching fishes in our estuarium and rivers near the sea, he also quarantine
them and acclimatize them then supply them to ornamental fish seller. He has
cement pools for this purpose, as well as various brackish, fresh and marine
aquariums. He is an aquascaper too. He showed me his lovely Echidna nebulosa,
which is very fat and is an adult (about 50 centimeters). He proudly told me
that he kept this eel for almost 2 years in this brackish water, and describe
how the Echidna survived a jump out of the aquarium for 2 hours! It's the best
eel for aquascaping marine tank, he said, because of durability, docility and
beautiful skin patterns. His tank is about the same size with mine, but mine is
a bit longer. I sampled and tested the water on the E. nebulosa tank with my
hydrometer, it's 1.012-1.014 after 3 tests. He told me that it was originally
the water from the river where the Echidna came from, but he does regular water
changes to acclimatize the eel. His aquarium does not look so appealing, with no
sandy bottom and only a handful of dead corals for the hideout of the Echidna.
But the Echidna does looks healthy. I wonder how that's possible, as to my
knowledge, E. nebulosa cannot survive anything below 1.018, so is this an
<Surviving and thriving are two different things. E. nebulosa are very hardy and
it's not the first time I hear it was caught in brackish waters.
1.014 is already mid brackish to high brackish. It's well possible the eel will
survive this for months or a few years, but nothing I can endorse for permanent
care based on the biology of this species.>
Knowing my love for eels, he showed me a low-water aquarium full of small eels,
he said they're totally brackish. I sampled the water and it's 1.008 - 1.010
after 3 tests, so rather similar to my aquarium. I asked about the Latin name of
the small eels and he said he has no clue (kind of expected).
So he gave me one, and asked me to study the eel and tell him what species it is
according to science, and I can give it back to him later. It's very very small,
maybe only 15 centimeter, and when I put it on my tank, it looks comfortable and
it snuggled itself under my largest Echidna rhodochilus. They looks compatible
in the pipe, they're almost the same in color and I noticed it also has white
blotches on the mouth. Is that a juvenile E. rhodochilus?
<Probably. Can't be sure. The pictures are rather blurry and dark.>
I look at Fishbase and noticed that Echidna leucotaenia also has white blotches
on mouth. What do you think it is, dear Marco?
<Based on what I see: E. rhodochilus. Echidna leucotaenia has more and different
Well, thank you for your time & have a nice weekend!
<No problem. Have a nice weekend, too.>
Best Regards, Ben
Re: Brackish moray ID 12/31/17
Hello Marco, I hope your weekend will be a splendid one!
When I look at the "mystery" eel and how similar it is to E. rhodochilus, I
think there is a big chance that you are right. The morphology are similar with
my larger E. Rhodochilus, and they even breath in the same rhythm.
<You can try to take better pictures (more light, acuity, more detail of the
head) of your mystery eel. Then we can work out a better ID. The last pics were
so dark and blurry, I can only guess its ID by a white spot I suspect. E.
rhodochilus is easily IDd by its uniform green to brown coloration and a larger
white spot at the rear part of the lower jaw which extends to the upper jaw
below the eye.>
What are other possible candidate? Maybe G. richardsonii?
<G. richardsonii can be IDd by a dark green dentritic pattern on a lighter
background color. Looks nothing like E. rhodochilus.>
I just read in a webpage that this species stay small, and also inhabit
estuaries. Will G. richardsonii thrive in 1.008-1.010?
<I doubt it. Though it does occur in shallow waters with brackish salinity it's
most often found in marine lagoons as far as I know.>
Are they as docile as E. rhodochilus throughout their lives?
<I kept G. richardsonii in the past. Mine could not be trusted with small
fishes, but got along well with other small morays.>
As you can tell, I like eels, not just morays. Actually Mr. Eko offered me one
of his newly-caught pike congers, the one with lovely blue-ish dorsal fins. Very
beautiful fish, but I heard it's rather vicious when wild-captured, so I
Back to our E. nebulosa. Mr. Eko told me that small E. nebulosus are frequently
being caught in the estuarium, while the larger ones are more common on coral
reefs and on rocky beaches. Maybe it's like what you said,
the younger ones hides in the estuarium, as they grow older and bolder, they
venture to the sea. If that's the case, then it's a humane practice to keep them
in full marine, as brackish is only a temporary hangout for them.
<I agree with that.>
Well, thank you for your kind patience and guidance. I will keep you informed
about my findings. Best Regards, Ben
<No problem. Looking forward to your findings. Cheers, Marco.>
Re: Brackish moray ID (file size fixed)
Good Day Marco,
I tried to take better pictures. This eel seemed to change colors
depending on its surrounding.
I hope these pics are clear enough for IDs.
<I fear they are not. I cannot see the coloration of the head and the
pattern on the body with enough detail.>
This eel and his friends were caught in a brackish river in north Java,
and has been living in a brackish tank for several months.
<Does your eel have the telltale white spots of E. rhodochilus or the
dendritic pattern of G. richardsonii? You can also compare your eel to
the ca. 65 species found in Indonesia here:
If you try to take pictures again use much more light (will also help with
sharpness) and maybe borrow another camera.
Thank you & Best Regards, Ben
Re: Brackish moray ID 1/3/17
Good day Marco,
Sadly you are right, I cannot get any better quality pictures with my current
cell phone. Also, my kitchen _is_ dark. Good for the morays, not so good for
photography :/ So, I will try to find a better equipment to make pictures. I can
take the eel out , bring it outside and take pictures, but I don't have the
heart, it's such a cute little eel... When I can borrow a better camera or cell
phone, I will make pictures again.
I checked out the Fishbase list and also this article below:
I observed the pictures of Bakasi (G. richardsonii) on the article above, indeed
the color and body-patterns are not similar with my eel. The Bakasis has
brownish and grayish color and beautiful body-patterns. Mine are plain.
Also, the Bakasis are described to be caught on the coastal areas.
<Also known from estuaries when young.>
Mine are caught in a brackish river, several kilometers from the sea. My eel has
the same body type and color with E. rhodochilus (brownish green/greenish brown)
but it has no white blotch on the cheek, just white blotch on the mandible. Most
logical explanation that it's a freak baby E. rhodochilus that has white blotch
on the mandible only.
<Probably E. rhodochilus if it's uniform brown to green with a single white
Or it's another species that happen to live in the same environment & behaves
similarly & has the same color.
Anyway, Mr. Eko said I can keep the eel for as long as I wanted, see if it could
live well and happy in my1.008 sg. If it thrives, he will let me have it. If it
doesn't look happy, he will take it back. So it's a good deal.
I joked to him, If it's a new species, I'll name it Muraena ekonii after him ;)
The Fishbase article is very useful, thank you for sharing! I have seen some of
the morays described there. Interesting that Fishbase mentioned some morays as
living in both marine and brackish (like Gymnothorax pictus)
and even all three environments (marine, brackish and freshwater) like the
Gymnothorax meleagris. Maybe most Gymnothorax species
<and many Echidna spp.>
are capable to enter brackish and freshwater from the sea, but not all has the
adaptability to thrive long-term in non-marine environments.
<That's what I think. Especially the young, the adults not so much.>
Well, thank you for the advice & discussions, I learn something new everyday!
Best Regards, Ben