Axolotl Care Guide
Authors:
Silvia Ochoa, Adam Mickle, and Karlie Bullivant.
The axolotl (Ambystoma mexicanum) is a fully aquatic salamander species. Axolotls are native only to Lake Xochimilco and Lake Chalco of Mexico, and are currently classified as critically endangered species in the wild; due to habitat loss, invasive predators, and environmental pollution. Now, this amazing amphibian thrives in captivity!
Unlike most salamander species, axolotls typically do not undergo metamorphosis to lose their gills and live on land. Instead, they retain their water-dwelling larval features for their entire life! This phenomenon of retaining larval features as an adult is known as neoteny, or paedomorphism. However, in very rare cases, it is possible for an axolotl to undergo metamorphosis into a terrestrial salamander.
In addition to their interesting appearance, axolotls are also known for their ability to regenerate limbs and organs, such as their heart and eye lenses, and even certain parts of their brain! This makes axolotls extremely valuable in medical studies, including cancer research and wound regeneration. Axolotls have long been considered a model animal for scientific research, with some of the first recorded observations dating back to the late 1800s!
Despite their appeal, axolotls have very specific environmental requirements as pets, making them more difficult to care for than some other animals. They require cold fresh water, often requiring a dedicated water chiller, and they are prone to illness and injuries. Their large aquariums require frequent water changes, many axolotls need to be fed directly with tongs, as they're naturally ambush predators that wait in one spot for their meal. Their waste also needs to be removed manually, often with a tool like a cooking baster, as well as manually brushing off algae in the aquarium and siphoning away any debris during routine maintenance. Well-cared for axolotls will have a lifespan of around to 10-15 years commonly, with some reports of 20+ year old individuals.
If you are ready for the responsibility, then this care guide will help you get started on giving your axolotl the best possible home.
Stages of Life
The average lifespan of an axolotl is approximately 10 years in captivity, however there have been reports of some axolotls living up to 15 years or older. Adult axolotls grow to be 23-30+ cm (9-12+ inches) long on average, reaching their adult measurements around 12-18 months of age. Many factors can influence rate of growth including environmental conditions, diet, age, injury, illness, or genetic factors. Although growth rate slows significantly as axolotls reach maturity, these incredible animals never truly stop the growing process!
Egg
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.
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 condition can be caused by malnutrition, poor living conditions, or genetic fault.
“Dwarf” axolotls have stunted, disproportional bodies. They can often be identified at a young age by their short, round torso and curvy or bent tail. This deformity is due to genetic influence, and is not considered ethical practice to sell once identified, as it's often a result of closely related genetic parentage. Axolotls impacted with the dwarfism gene will have the same behaviors and needs as any other axolotl; though some specialized care is required to help prevent impaction from over ingestion or accidental substrate inhalation, as they can be more susceptible to organ dysfunction. Dwarf axolotls have an average lifespan of 3-6 years old.
Housing and Tank Requirements
The Aquarium
We recommend 110 liters, or 29 gallons (30" x 12" x 18"/72cm x 30cm x 46cm), 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 with the most floor space you are able to get; the 180 liter, or 40 gallon "breeder style" (36" x 18" x 16"/91cm x 46cm x 40cm), tank is a much more suitable minimum tank size for an axolotl than the 110 liter (29 gallon).
When selecting the aquarium, consider wide and low aquariums over narrow and tall tanks. Axolotls will spend the majority of their time walking around the bottom of the tank, swimming occasionally, and they'll need ample space to explore and be comfortable. Bigger is always better for axolotls and their environments; there is no downside when it comes to increasing walking space and water volume! Larger quantities of water allows for greater waste dilution, keeping the water conditions cleaner also less prone to fluctuations in temperature and pH levels over time. Please note that juvenile axolotls grow so rapidly that using a smaller "grow out tank" is often unrealistic for this species.
Axolotls have a very heavy bio load, which means they produce a lot of nitrogen waste as a byproduct of respiration in their environment, resulting in rapid nitrate accumulation. The nitrate level is constantly rising in an established aquarium, and it must be kept below 20 ppm at all times with partial water changes and live plant management in order to not induce stress in axolotls. Larger water volumes will dilute nitrate production more efficiently and allow you to keep levels below 20 ppm more easily between routine water changes.
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.
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. For more in-depth information on substrates, read our article Which Substrate is Safe for Axolotls?
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.
Habitat
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 with their heavy bio-load, leading to increasing levels of nitrate build up in the aquarium. After your tank is fully cycled, it is important to perform weekly, or as often as needed, partial water changes in order to keep the nitrate level below 20 ppm at all times and maintain healthy mineral balance to support pH levels. Ammonia spikes are also common within axolotl tanks, so keeping track of your water parameters with a liquid testing kit is very important. Utilizing live plants in the aquarium is a beneficial way to help maintain lower levels of nitrate accumulation, and provide a more natural habitat for the axolotl.
Water Conditioner
As with any aquarium, a water conditioner must be used when adding any new water to the tank, to ensure there is no chlorine or chloramine that would otherwise damage the beneficial bacteria in the environment, or potential heavy metals that could be a toxin such as lead or copper. Aloe vera is an irritant to axolotls and a common ingredient in many products available in aquatic stores, so make sure that the water conditioner does not contain it before purchasing. 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, or Seachem Safe as it is axolotl-safe and has other added benefits such as cost efficiency. Seachem has recently released their own branded Axolotl Conditioner, which is just their Prime solution rebranded, so it is a safe option but be aware the cost may be more expensive to capitalize on market trends. Some other axolotl safe water dechlorinators are Aqueon Water Conditioner, API Aqua Essential, though be cautious that API Stress Coat and many other alternatives contain aloe vera and therefore are not a compatible option with axolotls.
Water Quality
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The water parameters of a fully cycled aquarium will be 0 ppm ammonia, 0 ppm nitrite, and between 5 and 20 ppm nitrate at all times, in order to not induce stress in the axolotl.
Increased amounts of nitrogen levels can be managed quickly by doing a partial water change. For example, a 50% water change will remove half of the nitrate present, as long as the new
water being added to the aquarium has 0 ppm ammonia, nitrites, and nitrates.
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Make sure that the pH of your tank falls between 7.2 pH and 8.4 pH.
A stable pH is more important than chasing a "perfect" number, as rapidly fluctuating pH levels can cause cellular damage with changing ionic density, leading to stress and potential tissue damage. Any changes in pH needs to be performed slowly to minimize stress, changing by no more than 0.2 of a degree per day, consistency is key!
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The ideal GH (General Hardness) for axolotls is 7-14˚ (125.3-250.6 ppm), and the ideal KH (Carbonate Hardness or Alkalinity) is 3-7˚ (53.7-125.3 ppm).
If your source water falls outside these ranges, it is possible to use supplemental minerals to support pH levels, like marketed alkaline buffers or sodium bicarbonate/baking soda (KH+); or calcium, magnesium, and potassium (GH+) supplements such as Holtfreter's solution, crushed coral/aragonite, or other market available mineral blends like Seachem Replenish.
Alternatively, water that has been stripped of its mineral content such as RO (Reverse Osmosis) DI (Deionized), or distilled water can be used to dilute source water that has extremely elevated mineral content, sometimes found in ground well water, which can lower pH levels effectively.
Tap water quality can vary greatly depending on region, urban utilities, and environmental influence, so it's essential to gather as much information possible about your source water. Detailed water reports are often available online for cities and towns with water treatment systems. Ground wells are recommended to be tested yearly at minimum. Additionally, home testing kits are available to purchase, with liquid testing or digital testing methods being considered the most accurate methods. Every test will have differing instructions, so it's important to perform the instructions exactly as stated for the most correct results! Tests that are done improperly can show incorrect results, most commonly under shaking nitrate testing solutions, showing a lower result than actuality.
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 by the beneficial bacteria. 0 ppm nitrate indicates that the aquarium is not cycled, unless the aquarium has a significant amount of live plants to combat nitrate production which can be tricky to accomplish with axolotl temperature requirements.
For more information on how to cycle your tank, please see our Cycling Guide.
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.
Temperature Management
It is very important to keep your axolotl’s water cool because they are an ectothermic species, meaning they rely on their environmental conditions to regulate their bodily functions including metabolism and respiration. Axolotls are most comfortable kept in water between 12-20˚C (53.6-68˚F). Temperatures higher than 20°C (68˚F) will quickly lead to stress and the development of disease. Increased water temperature raises metabolic rate and lowers available oxygen in the environment, leading to increased passive energy consumption as their systems work harder to maintain equilibrium. Over 22°C (71.6°F) for extended periods will be stressful and suppressing immune response, while over 24°C (75.2°F) can be fatal. On the other hand, temperatures lower than 10˚C (50˚F) will begin to slow metabolism, which is detrimental for long periods of time as they may struggle with full digestion of meals.
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.
Diet
Staple Foods
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 in bulk. 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 are one of the foods that 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. Read our Axolotl Nutrition article for in depth information on different food options and their nutritional value.
Treats
If you are looking to treat your axolotl, you may offer occasional treats, like waxworms, frozen brine shrimp or 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.
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.
Fired 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 be more active or eating when this occurs. This is completely normal and nothing to be concerned about.
Abnormal Behavior
Some behaviors may be indicators of stress or illness. These include forward curled gills, swimming erratically, writhing, loss of appetite, frequent uncontrolled 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
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. Please read our How to Determine the Sex of an Axolotl article for more detailed information.
Males
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.
Females
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.
Tank Mates
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. For a more in-depth information on tank mates, read our article Can Axolotls Have 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 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.
Accidental Breeding
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.
Shrimp
Some owners may use ghost (Palaemon paludosus) or cherry (Neocaridina davidi) 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. It is also recommended to quarantine any new additions for 30+ days, to monitor for potential parasites or disease, before introducing to an established ecosystem. In some cases, axolotl keepers will have additional aquariums for shrimp breeding!
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