Axolotls

Axolotl
Axolotl on sand underwater. Raj Kamal/Stockbyte/Getty Images

The axolotl may not be a very common pet but it is definitely a unique one. Axolotls are a type of salamander but unlike salamanders, they do not routinely undergo metamorphosis from the larval (with gills) to adult form and remain aquatic their entire life.  

Names: Axolotol, Ambystoma mexicanum, Mexican walking fish

Size: Between 6-18 inches long with about 9 inches being most common and over 12 inches being rare

Lifespan: Capable of living for over 20 years but more commonly about 10 years

Axolotls in the Wild

Axolotls are from the Xochimilcho Lake in Mexico where they are considered an endangered species due to there being very little of these waters left. Thankfully this depleted species (due to the growing Mexico City) is readily bred in captivity and is a popular subject for research due to their unique capability to regenerate entire limbs.

Axolotls can be found in a variety of colors including black, grey, golden, albino, white with black eyes, and other colors. The wild type, and most commonly seen in the remaining canals of Xochimilcho Lake is the nearly black axolotl.

Housing Axolotls

Axolotls can get quite large for a salamander so at least a 15-20 gallon fish tank (aquarium) is recommended, although the tank doesn't have to be full of water (the water only needs to be just deeper than the full length of the axolotl).

The tank should be kept in a cool room away from bright sunlight. The water temperature should be kept cool, between 57-68 degrees Fahrenheit (14-20 degrees Celsius), and never allowed to get above 75 degrees Fahrenheit (24 degrees Celsius). No special lighting is required for axolotls (unlike reptiles), and in fact a place to get out of the light may be appreciated, such as a flower pot laid on it's side or an aquarium type castle.

If gravel is used on the bottom of the tank it needs to be coarse gravel. Fine gravel might be ingested during feeding and cause an obstruction. Some owners opt to simply leave the bottom of the tank bare, although others believe this may stress the axolotls a bit since they can't get a foothold on the bottom of the tank without gravel.

Juvenile axolotls can be cannibalistic towards each other, so they are best raised in separate enclosures. Adults can potentially be housed together but watch for cannibalistic tendencies. Of course, if a body part gets bitten off by a tank mate, an axolotl can regenerate it over time but this should never be encouraged or allowed.

Axolotl Water

Most owners will find a filtered aquarium easier to maintain than one without a filter since unfiltered water will need frequent changing. However, if you do choose to have a filter on the tank, the filtration rate should be fairly slow and powerful filters that create strong currents should be avoided. Also, be sure that the filter intake is not in a position to trap the gills of your axolotl.

If you have a filter, safe cleaning would consist of using a siphon to vacuum the bottom of the tank and a 20 percent water change should be done weekly. If you are not using a filter, you will have to do a 20 percent water change every day or every other day. Never do a full water change as this creates a situation where the water chemistry changes too drastically for your pet axolotl.

Tap water should have any chlorine or chloramines (added during the water treatment process) removed using commercially available solutions. Never use distilled water and make sure the pH of the water remains between 6.5 and 7.5 (neutral).

Feeding Axolotls

In the wild, axolotls feed on snails, worms, crustaceans, small fish, and small amphibians. In captivity, they can be fed a variety of brine shrimp, small strips of beef or liver, earthworms (wild caught worms can carry parasites), bloodworms, tubifex worms (often fed to fish), other frozen fish foods, or commercial fish pellets (e.g. salmon or trout pellets). Pellets can also be purchased directly from the University of Kentucky where they breed and distribute axolotls to laboratories and classrooms through their Ambystoma Genetic Stock Center. Uneaten food should be cleaned from the tank daily to help keep the tank clean.

Terrestrial Axolotls

Under some circumstances, the axolotl can undergo metamorphosis into a terrestrial from, although this can be stressful on the animal and is not commonly seen. The conditions under which this would happen naturally is poorly understood but we know that the metamorphosis can be induced using changes in water characteristics, or by supplementing the axolotl with certain proportions of thyroid hormone. Of course the terrestrial form of the axolotl has a completely different set of care requirements. Trying to induce metamorphosis is not recommended, as this can place undue stress on an axolotl, and can significantly shorten it's life span.

Edited by Adrienne Kruzer, RVT