Swamp Eels, Family Synbranchidae, are often looked on as true
eels by the trade. They are not. Sure, they have a lot of eel-like
traits, being long of body and tapered, lacking pectoral and pelvic
fins, possessing only vestigial dorsal and anal fins, reduced or absent
scales and small gill openings...
These widespread (Africa, Asia, Mexico, Central
and South America) fishes are interesting aquarium specimens in their
own right. Not to add to the common name confusion, but one Swamp Eel
(Monopterus alba) is often referred to as a/the Freshwater Moray
Bear in mind the synbranchids can get to more
than a meter long, jump out like no tomorrow, and eat tankmates they
can get their capacious jaws around if you intend to try
Mystery "Tiger" Eel... ID 6/19/17
Thank you for the fascinating exposition about the world of fishes. My knowledge
of fish's sensory organs does not extend beyond knowing what are lateral lines
on fishes. So it's good to hear more details from you in regards to this matter.
<Glad to share.>
As an Indonesian, I feel blessed to live in a country with such rich
biodiversity, especially concerning fishes. At the same time, I often stumped by
the very diversity that my country's fishes exhibited. Take this fish (picture
attached), for example. Is this a Gymnothorax Polyuranodon?
<Quite possibly; but I do think Gymnothorax reevesii more likely.>
<<Thought this looked more like a Synbranchid... RMF>>
Such a lovely skin pattern, but it must served a purpose, maybe to confuse
predator fishes into thinking that it is a snake?
<Interesting thought. One issue is this though: Morays are nocturnal, and hide
by day, so their predators (if there are any!) wouldn't really see their colour
patterns easily, and more likely hunt by smell or vibration.
Still, who knows? Your idea definitely makes sense, and many animals mimic
Strange and beautiful eels often got fished out of our rivers and canals by
unsuspecting locals, and oftentimes I cannot even tell what species are they.
Local Indonesian, when shown the beautiful eel in the attached picture, will say
"that's Belut Macan Tutul!" (means: Tiger Eel), but there are lots of other
species which also being called "Tiger Eel". It's like the Pleco catfish, so
many different species and yet to local Indonesians, they're all "Ikan sapu
sapu". One name fits all :D.
Well, again thank you for the chat, and have a nice day!
<And likewise to you, too; Neale.>
What kind of Moray eel is this? 6/15/17
Good afternoon Neale and all the good people at WetWebMedia;
In an Indonesian discussion forum, I found this picture, the guy who posted it
said that he fished this moray eel in a river, several kilometres from the river
mouth/estuary. I wonder what Moray eel is this? It does not looks like
"freshwater" moray (Gymnothorax polyuranodon, we call it belut muara), so it
might be a new species?
<Mmm; I do think this is a Synbranchid eel (not a Moray): Ophisternon bengalense
<Cheers, Bob Fenner>
Re: What kind of Moray eel is this?
Hello Bob! Thank you for the reply. That was quick! And very informative too. I
never heard about this fish. We learn something new everyday. It's a very
fierce-looking fish, no wonder we all confused it with the moray!
<Synbranchids do look very similar... Neat animals (and tasty!)
Again, many thanks! *bowing*
<Sama sama my friend. BobF>
Eel not eating and strange behaviour
hi. my eel is refusing to eat.
<I can't really tell what the eel is from your photos. Is
it some sort of Synbranchus?>
i have read the information about the rearing of eels on your
website. however, i still cannot understand the strange behaviour
of my eel so i decided to write you this e-mail.
my eel is about half a metre long and i have been rearing it for
almost half a year. it lives in a tank (39.8cm x 25.4cm x 28cm)
but unlike the other eels which i read in your website, it lives
in the light and the surroundings are only dark at night when i
turn off the lights. there is no sand or stones on the bed of its
tank and besides a filter, 2 small red coloured fish and 5
prawns, there are no rocks or shelters where it can hide itself
in. however, it does not show any symptoms of escaping. it is
gentle and even allows me to touch and carry it in the water for
awhile before swimming out of my hands slowly. of course, i treat
it gently and carefully.
<If this is a Synbranchus, this nice behaviour is VERY
unusual. They're usually incredibly aggressive and
previously, i fed it tiny blood worms but then changed to frozen
prawn as it grew bigger. i feed it by dangling the food above its
eyes and it eats at least one small frozen prawn everyday.
<Do try not to use Prawns exclusively; they contain a lot of
thiaminase, and so can cause Vitamin B1 deficiency if used on
Occasionally, it will not eat for at the most 2 days. then it
will start feeding again. However, for the past 5 days, it has
not been eating at all and has been pushing its body against the
corner of the tank to great heights and putting it's whole
head above the water level when previously it was only his nose.
i have tried to feed it countless times, but to no avail. i am
afraid it may starve as it normally eats everyday but now its not
eating at all continuously for 5 days.
<By all means leave him without food for a few days. Then
offer something different. Earthworms are very popular with
carnivorous fish, and provided you collect them from somewhere
not sprayed with pesticides, they're cheap and safe. I
collect mine from the garden, underneath rocks and pots.
Alternatively, get a bag of mixed from seafood; these contain
squid, prawns and mussels, all of which your eel should
Please help me and my eel as it is really very dear to me. for
example, if i stand in front of the tank, it will swim towards me
and put its head above the water and look at me even if i am not
feeding it. sometimes, when i ask it to shake its body, and shake
my body to demonstrate, it will really do so! it has really
brought much joy to my family and i really hope that you will
help me bring it back to normal. i have attached some pictures of
it as i do not know the species. (sorry if the file size is too
big! ) I eagerly await your reply. thank you!
<He sounds a nice pet! Do research Synbranchus, particular
Synbranchus marmoratus, which is what I suspect your eel to be.
Re: Eel not eating and strange
thanks for replying me.
<Not a problem. But please, do try and use capital letters in
however, the fact that it has not been eating at all for six day
and still counting worries me immensely.
<Six days without food won't harm a Neon tetra, let alone
an adult eel. However, when fish go off their food it can mean
something is wrong with the environment. Review water chemistry
and water quality. I really do need to know what sort of
"eel" this creature is. Did you look at photos of
Synbranchus marmoratus? This is a big (150 cm) eel-like animal
that needs a big tank with lots of hiding places. If it's out
in the open all the time because there aren't any caves, it
will be stressed. In the wild they live in complex
what should i do to get it to eat again. it really hurts me to
see it get weaker and weaker each day and its skin colour
<If it's getting sick, I doubt this is because of lack of
food. Review its tank, particularly water quality. Don't tell
me the water is "fine" -- tell me at minimum what the
nitrite concentration is. Also how stable is the pH?>
what do you suggest it should do? would putting an enclosed place
for it to hide itself help?
otherwise should i switch back to feeding it the worms (a ball of
bloodworms which are each not more than 1cm long) like i did
<Insect larvae of all types will be good. So also earthworms
and river shrimps. Avoid Tubifex worms though, and never use
feeder fish. Both of these things cause much more harm than
i have been feeding it prawn for quite some time now. how can i
let it regain the vitamin b1 which it has lost overtime?
<By varying the diet. In particular, offer suitable sized
pieces of mussel. This herbivorous mollusk contains lots of
algae, and this is a rich source of vitamins. In the wild,
carnivores get a lot of their vitamins from the gut contents of
my eel once ate a small red coloured fish (live) and i read on
the Internet that eels eating goldfish/rosy-red fish and eating
everyday would cause liver problems. is it true?
<Yes, feeder fish and goldfish are bad. Minnows and Goldfish
contain thiaminase and ALSO lots of fat, and it's the fat
that damages the internal organs. One rosy-red minnow won't
have done any harm, but don't use any more of them. Even
putting aside nutritional problems, cheap fish are a source of
if it is, what should i do? please help me! thanks. :)
<Let me know about the water chemistry and quality, and also
either identify the "eel" or send me a SHARP photo so I
can identify it for you. Cheers, Neale.>
Re: Eel not eating and strange behaviour,
Synbranchnid 9/16/08 Hi again!
<Hello,> Thank God! My "eel" is finally eating
again after starving for a whole week. Actually, i didn't
really do much. I just draped a piece of black cloth over half of
the tank to replicate the dark environment of a cave, seeing if
it would help. After i came home from school, as per normal, i
stood over the tank and called its name. Miraculously it looked
up and swam towards me, swaying its body happily. Noticing that
it seemed like it had got well, i fed it and fortunately, it ate.
:D <Ah, success! Does seem that environment was the
factor.> Can i feed it shellfish and squid? are they
detrimental to its body? You mean that i can feed it prawn but
not everyday right? <Squid is excellent, and so are molluscs
of all kinds, mussels, clams, etc. Small pieces of lean white
fish (such as tilapia) are good, too. Avoid oily fish though
(salmon, tuna, etc.)> Would putting pipes in its tank instead
of rocks be ok? <PVC pipes or ceramic pipes are both fine.>
And would you recommend me to put sand on the bed of the tank? As
the fact that i am afraid that cleaning a tank with sand would
not be easy and there would be a lot of dirt caught in sand
causing bacteria to multiply which may cause internal or external
fungal or bacterial infections. <Smooth silica sand is fine in
aquaria. I use it all of mine! Avoid "sharp" sand
though. Silica sand is sold in garden centres and is very cheap.
It's actually very clean, because dirt can't sink in
between the grains. So you can see the dirt, and easily remove
with a net, or better still, a turkey baster. Use a thin layer,
maybe 1 cm or so, in tanks without plants. Add a few burrowing
Melanoides snails if you like, and they'll keep it spotlessly
clean.> Just sent this e-mail to tell you the good news and
ask some questions. I will send clearer and sharper pictures
soon! thanks! :D <Look forward to the pictures! Cheers,