Freshwater Moray Eels
By William Berg
Aquarticles
This article will primarily depict my experiences over the years with Gymnothorax 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 120 gallon for these fish, which grow to about 24". 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 (silversides) 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. 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.
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. 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.
