April 19, 2005
How to care for Typhlonectes natans
Typhlonectes natans is an aquarium pet and needs similar care to that of fish.
Typhlonectes natans are from South America. So standard Amazon tank setup is the ideal.
Specifically: low pH (6.6), soft water, 78-86 F, no salt. (But see the debate about salt that’s been ongoing on the discussion board… some salt may be OK as long as the specific gravity doesn’t change often)
From our experience (blind leading the amphibious) they have survived extended periods at 7.7pH, medium hard, 65 F, and 2tbsp aquarium salt/gallon. Not ideal. They seem much happier at higher temps, much more active. Rapid changes in salinity cause them to form gas bubbles under their skin, which go away after about a day. Our current tank is 6.8 pH, medium, 82 F, no salt.
The water should be biologically and mechanically filtered. UGF, power, and canister filters will all do the job. The eels will do ok in non-filtered water, but your fish will not. Typhlonectes natans is not more sensitive than most fish to ammonia and nitrtes.
We don’t know for sure what they eat in the wild, so we’ve done a lot of dietary guess work. They’ve eaten every food we’ve offered, if they could catch it. They have hook teeth which point backwards, so it’s very hard for them to let go of food. The eels have bitten us many times and its definitely not at all painful.
Favorite food: dried tubifex cube. They have successfully eaten frozen bloodworms, minced beef heart, dried tubifex, dried shrimp pellet, algae wafer(!), live 2-inch decorative shrimp (the eel bit the poor thing in half and downed the back end in one swallow.), ~1 in. snail (but not the shell). When they could catch it they ate glass shrimp, live bloodworms, and brine shrimp, but all with a low catch rate. Eels can be handfed.
They have tried to eat fish, rasbora and tetra, but couldn’t swallow them so we had to pry the dead fish out of the eel’s mouth. It is very rare that they actually catch or even chase fish, so we have not separated them from the eels. We lose about one small fish per year per eel. The eel seems to have a detachable jaw so it can eat things slightly larger than it’s mouth using the snake method, but can’t eat big things like rasbora.
Amounts & Schedule: Whenever they start nosing around and under things, we throw in about 1/4 Tbsp.shrimp pellets.
Often and for no apparent reason they will stop eating. This has happened many times to us. Our suggestion is to try switching to live food if the eel hasn’t eaten for a couple weeks. Eels can go for a long time without food, but may start to hunt their neighbor fish. You can go on vacation and not have them fed.
Companion fish are necessary if you have biological filtration. Eels do not seem to contribute enough ammonia on their own to keep a healthy bacteria colony going.
Since eels are very messy and crumbly eaters, it is also important to have someone to eat the leftovers. The best we’ve found so far is the Cory catfish (corydoras sp.). They are fast enough to get away from nosing eel heads, and not so competitive and large that they steal the eels’ food. They are also Amazon area fish, native to the area from which T. natans originates. We found that Mollies and Gourami were both too aggressive and didn’t allow the eels time to find the food. Most tetra-like fish and rasbora don’t eat off the bottom enough to be of use for that purpose.
It’s also good to have a fish to eat the eels’ shedded skin. This alleviates the need for you to clean it out. Mollies, Gourami, and Monk Tetra have been very eager to help the eel by pulling at it’s trailing old skin. This process doesn’t hurt the eel. Cories do not eat eel sheddings.
Caecilians like to dig up and sleep under the substrate. They especially dig under any plants and structures (ours like slate). Too heavy or dense substrate seems to discomfort them, and anything sharp will hurt their nose or cut their skin. We have had them trap their heads in plant-pots to the point where they needed help getting out.
In the wild, they probably have sand or silt, so a clay substrate might be ideal, but it can be hard to keep sand clean. We had them in a tank with an UGF but it seemed to make digging more difficult by pulling the gravel down and compacting it. Now we have them in a temporary setup with a sponge corner filter. Without the UGF they seem to have an easier time getting under the gravel, which means we see them less, but they are happier. They do avail themselves of sunken wood or slate rather than expend the effort to dig when possible.
From our experience, they have an easier time digging in large gravel. The larger the grain of the gravel, the easier it is for them to get their nose between the pieces. It seems that if they can get their nose into a space, the rest of their body will follow.
Since Typhlonectes natans breaths air (not water) they must be able to stick their heads out of the water. Always leave at least 1/2 inch (13mm) between the lid and surface of the water. Although Typhlonectes natans can live out of the water for a long time in a moist rainforest, most will not survive the harsh climate of your house. Please make sure the lid is on tight with no holes. If they get out they will start to dry up. If you discover your eel stuck to the carpet behind the couch, you may still be able to save it’s life by putting it back in it’s tank. Tape all the openings and flaps on the top of the tank with masking tape. The tape will get gummy after a month or so, and will need to be replaced.
While we have kept a 12 inch rubber eel in a 20 gallon tall hex tank, they seem much “happier” if they can stretch out both horizontally and vertically on occasion. They will swim up for air at least a few times a day, so they need a tank at least 16 inches tall. If the tank is too short, they are capable of climbing out through small holes for airline and heaters. Horizontally, they seem to like to swim in the open every few days, so a tank at least 1.5 times as long as them is necessary, and 2 to 3 times their length would be excellent.
They seem indifferent to lighting, being most active in the evenings, whether the light is on or off. We have no idea if they can even see, although their eyes are well-defined and not milky like most blind animals. (Note: we have observed them responding to motion outside of the tank, although whether this was due to vibration through the floor or some poor sense of sight we aren’t entirely sure.)
They need to hide often, and prefer an actualized environment where they can indulge in climbing and clinging, curling up wrapped around branches of plants or outcroppings of rock, or woven through openings in decorations. A well-perforated structure and a few rubber eels will provide both you and them hours of enjoyment.
by Rebecca Herndon and Seth Morris