Axolotl Care Guide
The axolotl, sometimes referred to as 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 for its entire life 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.
Stages of Life
The average lifespan of an axolotl is approximately 10 years, however there have been reports of some axolotls living up to 15 years or older. Adult axolotls grow to be 23-30 cm (9-10 inches) long on average.
Axolotls begin their journey through life when a female lays hundreds of small, gelatinous eggs.
Over the course of two weeks, the eggs develop into tiny axolotl larvae.
Mini and Dwarf Axolotls
Axolotls that do not reach the average size are often called "minis". Minis can be as small as 15 cm (6 inches) when fully grown, but still have proportional bodies. This stunted body can be caused by malnutrition and poor living conditions.
“Dwarf” axolotls have stunted, disproportional bodies. They can often be identified at a young age by their short, round torso and curvy tail. This deformity is due to genetic factors.
Housing and Tank Requirements
We recommend 110 liters (29 gallons) per axolotl as the absolute bare minimum aquarium size for axolotls of any size or age. This takes into account both water volume and floor space. However, we strongly recommend getting the largest tank you are able to get; the 180 liter (40 gallon breeder) tank is a much more suitable minimum tank size for an axolotl than the 110 liter (29 gallon).
Bigger is always better for axolotls. Please note that juvenile axolotls grow so rapidly that using a smaller "grow out tank" is unrealistic for this species.
Axolotls have a very heavy bio load, which means they produce a lot of waste, resulting in a lot of nitrate. The nitrate level is constantly rising in an aquarium, and it must be kept below 20 ppm at all times with partial water changes in order to not induce stress in axolotls. Larger water volumes will dilute nitrate more and allow you to keep it below 20 ppm more easily.
When considering a tank for your axolotl, it should be noted that a longer, wider tank is more suitable than a tall, thin tank, as axolotls will utilize floor space much more than open water.
Another thing to consider is that some axolotls may accidentally 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 need a breathable lid, such as egg crate. A mesh reptile lid, however, will rust over time and leak into the tank.
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. Any substrate with particles larger than 2 mm diameter is by definition gravel. When a larger axolotl ingests fine sand, it will usually pass through them without any issue.
However, younger axolotls cannot be kept safely on sand because they are still too small for even fine sand to safely pass through them. We recommend waiting until your axolotl is at least 15 cm (6 inches) long before using a sand substrate.
Some other options are having no substrate at all or using rocks that are significantly larger than the axolotl's head. 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 untreated tiles to dress it up.
Providing your axolotl with an enriching and comfortable environment is also important. Putting plenty of hiding spots in your tank is one way to accomplish this. Some axolotls may even interact with bubbles from air stones. Rearranging tank decorations from time to time provides a new layout for your axolotl to explore for enrichment.
Adding live plants is a possibility for an axolotl tanks. However, it should be noted that axolotls do not have eyelids and are sensitive to light. Since low lighting is the most suitable option for axolotls, you will only be able to include plants that can survive in low light cold water, such as Anubias, Elodea, java fern, java moss, Marimo algae balls, and many more.
If you do add aquatic plants to your tank, it is recommended to avoid using any fertilizers. The low maintenance plants that can survive in an axolotl tank typically do not require supplementation, and it is safest to avoid adding extra chemicals to an amphibian tank, since their semi-permeable skin absorbs much more of it than fish would.
Ample hiding spots provide a more comfortable environment for your axolotl.
Marimo balls can be used with axolotls as long as they are larger than the axolotl's head.
Aquatic plants provide a great hangout spot for axolotls.
Some common houseplants, such as pothos and monstera, can be partially submerged in your tank as well, to both help absorb some nitrate and provide hangout spots for your axolotl.
Water Parameters and Temperature
Cycling Your Aquarium
Like all aquatic pets, axolotls require a fully cycled aquarium before they can be added to the tank. It is easiest to refrain from purchasing your axolotl until after your aquarium is fully cycled, as cycling can take 4-8 weeks when done from scratch, without the help of already seeded filter media. Please see our Cycling Guide for a step-by-step walkthrough explaining how to cycle your aquarium through the nitrogen cycle.
Weekly Water Changes
Axolotls are messy, and will quickly pollute their water. After your tank is fully cycled, it is important to perform weekly water changes in order to keep your nitrate level below 20 ppm at all times. Ammonia spikes are also common within axolotl tanks, so keeping track of your water parameters is very important.
As with any aquarium, a water conditioner must be used when adding any new water to the tank. Aloe vera is an irritant to axolotls, so make sure that the water conditioner does not contain it. Conditioners containing aloe often contain words such as "natural", "plant", "herbal extract", "slime coat", or "stress". The water conditioner should also not contain iodine.
The most commonly recommended water conditioner for axolotls on the market is Seachem Prime, as it is axolotl-safe and has other added benefits.
The water parameters of a cycled aquarium will be 0 ppm ammonia, 0 ppm nitrite, and between 5 and 20 ppm nitrate at all times. Make sure that the pH of your tank falls between 6.5 and 8.0. For more information on how to cycle your tank, please see our Cycling Guide.
Even though nitrate should always be kept below 20 ppm, a fully cycled aquarium would never have as low as 0 ppm nitrate because animal waste is constantly being emitted into the water and processed into nitrate. 0 ppm nitrate indicates that the aquarium is not cycled.
Test Your Water Frequently!
The well-being of animals cannot be judged only by looking at them.
The only real way to know if your axolotl is stressed is by always knowing your water parameters.
Water can easily become toxic if not monitored closely.
It is very important to keep your axolotl’s water cool. Axolotls are most comfortable kept in water between 15-20˚C (60-68˚F). Temperatures higher than 20°C (68˚F) will quickly lead to stress and the development of disease. On the other hand, temperatures lower than 15˚C (60˚F) will begin to slow metabolism, which is detrimental for long periods of time.
A couple ways to lower temperature consistently are with clip-on fans or aquarium chillers. Frozen water bottles can be used temporarily, 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. See our article How to Lower the Temperature in an Axolotl Tank for more information.
Axolotls require earthworms or night crawlers in order to have proper nutrition. Earthworms and night crawlers 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 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.
If you are looking to treat your axolotl, you may offer occasional treats, like waxworms, frozen bloodworms, Repashy Grub Pie, and blackworms. Keep in mind that these foods are classified as occasional treats, due to not being as nutritionally complete as earthworms.
Live cherry or ghost shrimp tank mates are also an option for your axolotl to snack on. 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.
Do Not Feed
Feeder fish such as goldfish and minnows contain thiaminase, which will cause a thiamine deficiency in your axolotl when they are eaten consistently. Other fish tend to nip at and damage the axolotl's gills and slime coat, and fish from pet stores will also easily spread diseases and parasites. In addition, many fish have different temperature requirements than axolotls and cannot be housed comfortably in cold water.
Most insects should not be offered to axolotls. Insects and their larvae often contain chitin, which is indigestible to axolotls. Insects also do not fulfill the dietary requirements of axolotls.
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.
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.
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.
While axolotls typically cannot be definitively sexed until they are around 12-18 months old, there is no set age within this range to determine the sex of an axolotl, as every axolotl develops at a different rate.
The average age to identify a male is around 12 months, but they can be identified as early as 5 months or as late as 18 months depending on when they develop an enlarged cloaca. In uncommon cases, an axolotl can be identified as a male as early as 5 months if the cloaca is already becoming visibly enlarged, but they can also be late bloomers and take as long as 18 months to present an enlarged cloaca.
A male cloaca is visible as a protruding bump behind its back legs. Male axolotls will typically have slimmer body shapes with longer tails. One way to differentiate male and female cloacas is to note that a male cloaca bulges from the sides.
While the males have a very obvious sign of their sex, female indicators are much less definitive. 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.
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. Some parasites may take even longer than 30 days to become apparent.
Unfortunately, axolotls generally do not do well with tank mates. The safest tank mates that you can keep with your axolotl are small shrimp.
Although they may often invade each other's personal space, axolotls are not social animals. They are a solitary species that does 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 the situation is neutral at best. Keeping more than one axolotl in the same enclosure poses danger, as they easily mistake each other for food, may mate and produce accidental eggs, and more than one axolotl in a small aquarium will cause nitrate levels to rise quickly.
Risk of Injury
Axolotls often mistake one another for food and will bite each other. If axolotls are housed together, they must be fed far away from each other in the tank to avoid injury. Once the axolotl sees its owner, it will begin to equate anything moving nearby with food, which easily results in nipping. They must also be fed frequently enough to avoid nipping in general. Axolotls can easily eat each other if size difference allows one's head to fit inside the other's mouth.
If juvenile axolotls are housed together, there is a high probability that they will turn out to be opposite sex. If a male and a female are together, then they will breed. If you are not intending to breed, then you will end up with hundreds of accidental eggs scattered throughout your tank.
It is very important to remember that eggs from parents with undocumented genetic history and lineages should never be raised. If your axolotls have accidentally bred, the eggs should be culled humanely by freezing in order to prevent more harmful and unknown genes from being spread.
The population of captive axolotls is currently suffering from various genetic issues, so it is imperative that we only ever breed axolotls from ethical breeders with tracked 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.
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. It is recommended to not add shrimp to your axolotl tank until your axolotl is at least 15 cm (6 inches) long to ensure that the axolotl can swallow them safely.
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