Ambystoma mexicanum


The axolotl, sometimes called the “Mexican walking fish”, is a fully aquatic salamander native to only lakes Xochimilco and Chalco in Mexico. Unlike the majority of other salamander species, the axolotl does not go through metamorphosis to live on land, and instead keeps its feathery gills and other larval features in a phenomenon known as neoteny.

 

In addition to their interesting appearance, axolotls also possess the ability to regenerate limbs and organs, such as their heart and even certain parts of their brain. If you have decided that the axolotl is just the pet for you, then this care guide is the perfect place to start.

 

Lifespan

 

Egg

Axolotls begin their journey through life when a female lays hundreds of small, gelatinous eggs. Over the course of two weeks, the eggs begin to develop into tiny axolotl larvae. During these two weeks, the embryos develop a tail, gills, and eyes before finally hatching.

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Juvenile

Hatchlings are born only eating live food. Young axolotls will generally grow 1-2 inches per month as juveniles when properly nourished, and growth may begin to slow down around 6 months old. Around 12-18 months old, the axolotl will be nearly finished growing.

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Adult

The average size of an adult axolotl generally varies between 9 and 12 inches (23 to 30 cm) with some exceptions. Axolotls called “minis” do not reach the average size. Minis can be as small as 6 inches (15 cm) when fully grown, but still have proportional body features. "Mini" axolotls can be caused by stunting due to malnutrition and/or being subjected to poor living conditions. There are also “dwarfs”, which have stunted, less proportional body features. Axolotls have an average lifespan of 10 years, but there have also been reports of some axolotls living up to 15 years or older.

 

Housing and Tank Requirements

 

The Tank

We recommend the bare minimum tank size for one axolotl to be 30 gallons (114 liters), and 10 gallons (38 liters) must be added to the tank size with every additional axolotl in the tank. When considering a tank for your axolotl, it should be noted that a longer, wider tank is better than a tall and thin tank, as axolotls will utilize floor space much more than open water. A standard 20 gallon long tank may be used as an absolute bare minimum size tank. However, due to its smaller size and the heavy bio load of an axolotl, it would need multiple water changes per week in order to keep the nitrate level below 20 ppm at all times. A 30-40 gallon tank is a much more suitable bare minimum for one axolotl.

 

Another thing to consider is that some axolotls may jump from their tank if the water level is too high. Jumping can be prevented by keeping the water level a couple inches below the tank’s rim, or by using a lid. Keep in mind that if you are using fans to cool your tank, you will want a breathable lid, such as egg crate or a mesh reptile lid.

Substrate

There is always an impaction risk when using loose substrate with axolotls because they will always ingest the substrate of the tank. It is important that any gravel, small rocks, and small decorations the size of the axolotl’s head or smaller are avoided. A very soft, fine sand with less than 1 mm grain size poses the least risk for axolotls over 6 inches long. Any substrate with particles that have a diameter over 2 mm is by definition gravel. If a larger axolotl accidentally ingests fine sand, it will usually pass through them without any issue.

However, younger axolotls should not be kept on sand because they are still too small for even fine sand to safely pass through them. Some other options are to have no substrate at all or use large rocks that are larger than the axolotl. A bare bottom tank can be easier to keep clean, but may not provide as much grip for your axolotl. If you do not fancy the look of the bare glass, you could even use tiles to dress it up.

Habitat

Providing your axolotl with an enriching environment is also important. Putting plenty of hiding spots in your tank is one way to accomplish this. Some axolotls may even enjoy bubbles from air stones or bubble walls.

 

Adding live plants is a possibility for an axolotl tank as well. However, it should be noted that axolotls do not have eyelids and are sensitive to bright light. Since low lighting is the most suitable option for them, you will only be able to include plants with low light requirements, such as anubias and java fern.

 

If you do add aquatic plants to your tank, be sure to avoid using any fertilizers. The low maintenance plants that can survive in an axolotl tank do not require supplementation, and it can be dangerous to add extra chemicals to an amphibian tank since their semi-permeable skin absorbs much more of it than fish would.

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Water Parameters and Temperature

Cycling

Like all aquatic pets, axolotls require a fully cycled aquarium before they can be added to the tank. Axolotls are messy, and they will quickly pollute their water. After your tank is fully cycled, it is important to perform at least one weekly water change, if not more in order to keep your nitrate level below 20 ppm at all times.

 

Just like with any aquarium, a water conditioner must be used when adding any new water to the tank. Ammonia spikes are also common within axolotl tanks, so keeping track of your water parameters is very important.

 

The water parameters of a cycled aquarium should be 0 ppm ammonia, 0 ppm nitrite, and a nitrate reading between 5 and 20 ppm at all times. Make sure that the pH of your tank falls between 6.5 and 8.0. For more information on cycling your tank, see our Cycling Guide.

Although nitrate should always be kept below 20 ppm, a fully cycled aquarium would never have exactly 0 ppm nitrate because the animal's waste is constantly being converted into nitrate.

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Temperature Management

It is very important to keep your axolotl’s water cool. Axolotls should be kept in water that is between 60-68˚F (15-20˚C). Temperatures higher than 70°F (21°C) can lead to stress and the development of disease.

 

A couple ways to lower temperature consistently is through clip-on fans or aquarium chillers. Frozen water bottles filled with conditioned water can be used as well, but are best used for emergencies. It is very important to have a consistent means of keeping your axolotl’s tank within a comfortable range, and fans and chillers do a much better job of this.

 

Diet

Staples

Axolotls require earthworms or nightcrawlers in order to have proper nutrition. Earthworms and nightcrawlers meet the nutritional requirements of your axolotl better than any other option, as they contain over 60% protein and a Ca:P ratio greater than 1. On top of that, they are typically easy to find in bait shops, pet stores, or order online. Starting a worm farm may be a beneficial investment for supplying your axolotl with food.

 

To supplement the axolotl's main diet of worms, axolotl pellets may also be fed. There are several axolotl specific pellets available. If you are unable to find axolotl pellets, then sinking carnivore pellets can be used.

Treats

If you are looking to treat your axolotl, you may offer occasional treats like frozen bloodworms. Cherry or ghost shrimp are also an option. However, if you choose to keep shrimp with your axolotl, it is safest to breed your own, or at the very least quarantine and medicate any that you purchase from pet stores for at least 30 days to screen for diseases and parasites before introducing them to your axolotl’s tank. Repashy Grub Pie can be offered, but only as an occasional treat, due to its low nutritional value.

What Not to Feed

Some foods, such as most insects, should never be offered to axolotls. Insects and their larvae often contain chitin, which is indigestible to axolotls. In addition to this, insects do not fulfill the dietary requirements of axolotls.

 

Behavior

General

Axolotls will generally sit around their tank all day. They are opportunistic hunters that will stay in the same area waiting for prey to pass by instead of actively searching for it. You may also see your axolotl walking along the bottom of the tank as well as occasionally swimming around.

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Firing Up

Axolotls may even “fire up” at times. When this happens, axolotls may take on a lighter color and their gills become more red for a brief period of time due to increased blood flow. Axolotls may also be more active when this occurs. This is completely normal and nothing to be concerned about.

Abnormal

Some behaviors may be indicators of stress or illness. These include forward curled gills, swimming erratically, writhing, loss of appetite, frequent floating, scratching at their gills with their back leg, or a fold in the very tip of their tail. If your axolotl exhibits any of these behaviors, test your water parameters right away.

 

Determining Sex

 

Males

Axolotls usually cannot be sexed until they are around 1-1 ½ years old. An axolotl can be identified as a male earlier than this if they develop an enlarged cloaca, which is visible as a larger bump behind its back legs. Male axolotls will typically have slimmer body shapes with longer tails as well.

Females

Female axolotls are more difficult to sex than males. While the males have a very obvious sign of their sex, female indicators are much less noticeable. Female axolotls are typically more plump than males and may have a shorter tail. A female axolotl cannot be identified with 100% certainty until it is around 18 months old, as even a plump, short-tailed axolotl could turn out to be a male.

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Tank Mates

 

Other Axolotls

Unfortunately, axolotls generally do not do well with tank mates. The safest tank mates that you can keep with your axolotl are other axolotls of the same sex and of similar size. If one axolotl's head is small enough to fit inside the other's mouth, then there is a considerable risk of the smaller axolotl being eaten.

Although they may invade each other's personal space, axolotls are NOT social animals. They do not care either way whether they are housed with another member of their species, and they feel no sense of company nor loneliness. There are no benefits to cohabiting axolotls, and keeping more than one in the same enclosure is entirely up to the owner's preference.

 

If a male and a female are kept together, then they will breed. If you are not intending to breed, then you will end up with hundreds of eggs scattered throughout your tank. It is also important to remember that eggs from parents with undocumented genetic history should never be raised. If your axolotls have accidentally bred, the eggs must be culled humanely by freezing in order to prevent more harmful/unknown genes from being passed down.

 

The population of captive axolotls is currently suffering from numerous genetic issues, so it is imperative that we only ever breed axolotls from reputable breeders with known genetics and lineages. It should also be noted that female axolotls should not be bred more than once every 6 months. Overbreeding is stressful to female axolotls and may make them more susceptible to diseases. 

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Snacks

Some owners may use ghost or cherry shrimp for detritus cleanup in their axolotl tank, but they will most likely get eaten by the axolotl. As with all aquatic animals, make sure that if you do decide to get your axolotl a tank mate to quarantine them for at least 30 days to screen for parasites and diseases before introducing them to the tank.