Freshwater Moray Eels
By William Berg
of Sweden, for aquaticcommunity.com
Aquarticles
This article will primarily depict my experiences over the years with Gymnotorax
tile, but can to a very high degree be applied to any of the so-called freshwater
moray eels.
I would like to start by giving a description of my experiences with G. tile.
You often hear that these fish are hard to keep and usually die after a few months, are
hard to get to eat and are usually so weakened when you get them that they are beyond
saving. I have kept this species for a few years in different aquariums and have found
that it isn't a hard fish to keep if you just meet a few small demands. If these demands
are met they eat just about anything and even eat food out of your hand above the water
surface - that is, if you are brave enough to risk that they bite you by mistake (and take
my word for it, they carry a mean bite). The rumours about them being weakened by
transportation are usually just rumours. By my account these fish can recover from just
about anything.
The "secret" of keeping morays is to understand that these animals are very
easily stressed if not given the right environment. And if they feel stressed they'll stop
eating and slowly fade away over 2-3 months, which explains many of the rumours
surrounding these fishes.
Water conditions
First of all I would like to stress that these fish are not really freshwater fishes, even
if they can be found from time to time in freshwater. They are much rather kept in
brackish water. This said, I should add that it is possible to keep these fish in
freshwater more permanently, however the fish are much more sensitive in freshwater and
therefore this is not recommended if you don't have extensive experience with these
species, and even then brackish water is preferred.
Aquarium
I recommend a big aquarium, at least 540 litre/120 gallon for these fish, which grow to
about 60 cm. The aquarium should be decorated with a lot of hiding places. I will
return to decoration later.
Feeding
If the specie's other demands are met, feeding freshwater moray eels shouldn't give you
any problem - they accept most kinds of live and frozen food. They usually don't accept
pellets. A varied diet is always preferable. I usually feed my eels a diet based on frozen
shrimp (the kind you buy in your grocery store) and frozen fish that isn't too fat. Once
in a while I'll give them live fish, but don't be surprised if the fish survives a few
days - sooner or later it will become food. The diet can be varied a little more with
different meats, crayfish etc. - just use your imagination. However don't feed the eels
pork, since it's too fat.
Company
It's a bit tricky to find good tank mates for morays, since they eat anything small
enough, are easily stressed so therefore can't be kept with too aggressive species, and
are brackish water species which further narrows the field of potential companions.
First of all I recommend you to keep more than one moray in your aquarium. They are not
aggressive towards each other and often share caves, which gives a nice touch to the
aquarium. However you might still want to have some other species in the aquarium and I
would then like to recommend bigger dats which usually don't hassle morays, and maybe
scats, monos, or puffers. Another possibility is pleco/ancistrus species. Morays don't eat
ancistrus if they are too big to be swallowed in one gulp. Other large eels are another
suggestion.
Use your imagination but remember what I stated above and be patient if trying new
species. Just because the morays haven't eaten a fish in a few days doesn't mean they
aren't going to. I recommend that you wait at least 14 days before deciding that it is
safe to get more specimens of a species. I would also like to remind you that if the
moray, or any other fish for that matter, has grown up with a fish and hasn't eaten it, it
doesn't mean that it won't eat another new fish of the same species and size.
I sometimes hear people recommend to keep tiger barbs or danios with this species.
However I would like to discourage this. My experience is that these fish always end up
inside the morays within a few weeks.
Tank setup
The most important thing to remember when you decorate is to create a lot of hiding places
and narrow caves. I also promote having plants in the tank, since plants create dim
corners and produce even more hiding places, and calm the fish down even further. I
recommend using anubias species and Java ferns that don't have to be planted in the soil,
and which create good hiding places since they have sturdy leaves. These plants also
tolerate slightly brackish water. Below you can see the tank set-up that I usually use.
The aquarium in question is a standard 540 L.
The green colour represents plants. The lower left corner is planted with anubias which
grows to about 20 cm, and the other green spots represent Java fern. I usually also have
small anubias plants growing on the rocks.
I try to use rocks of different heights and make sure there is not more than maybe 10
cm between the different rocks in the background. I also put plants in the bigger spaces
to make it feel safer for the morays. Always try to have at least two, preferably three,
large cave systems. In the diagram above you can see this illustrated by large rocks
laying on small rocks. If you want to improve your morays' living conditions even more you
can put a few PVC pipes in your tank in different sizes, large enough for your morays.
However if you have built good rock formations this isn't necessary.
The important thing is to create a lot of good hiding places. How you do this is less
important - if you like sunken model ships go for it, just don't use anything toxic. I
would also like to warn about using roots in your morays' tank since this will effect
water conditions in a way that is negative for morays.
Other moray species
This is a list of moray species that wander into brackish and freshwater and which can
occasionally be found in the trade. Species identification in stores is usually very
unreliable.
Echidna rhodochilus, Gymnotorax tile, and Gymnothorax afer are the
three most commonly available species. These species are, along with Gymnothorax
polyuranodon, the species most suitable for aquariums with brackish water.
Other species which occasionally wander into brackish waters include:
· Anarchias seychellensis
· Echidna leucotaenia
· Gymnothorax fimbriatus
· Strophidon sathete
· Thyrsoidea macrura
· Uropterygius concolor
· Uropterygius micropterus
Final thoughts
Freshwater moray eels can be a very pleasant experience if you are willing to meet their
demands. I find healthy morays a beautiful and interesting addition to any aquarium that
meets their requirements, and it's a pleasure to see them lurking in their caves. The fact
that after a little training (1 week) they will elevate a large part of their body above
the water's surface to take food out of your hand doesn't hurt either, and makes a nice
trick for guests. And since these fish, if well taken care of, live to be 35 years old
they might become long time acquaintances.
But don't take my word for it, try keeping morays yourself, but only if you are willing
to give them the environment they require. Otherwise your experiences most likely will be
disappointing, and add to the rumours surrounding these fishes that they are impossible.
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