Axolotls (Ambystoma mexicanum) look like a fantasy animal — feathery external gills, a permanent smile, and the ability to regrow limbs. They are also one of the most commonly misunderstood pets in the hobby: they are cold-water amphibians, and most of what kills them in home aquariums comes down to warm water and an uncycled tank. Get those two things right and an axolotl is a calm, long-lived pet that can live 10–15 years.
Before you buy one, check your local rules. Axolotls are banned or restricted as pets in California, Maine, New Jersey, and Washington D.C., and require permits in some other states such as Hawaii and New Mexico. Check the official rules for your state before ordering — a seller shipping to you does not make it legal.
At a glance
- Adult size: 9–12 inches (23–30 cm)
- Lifespan: 10–15 years with good care
- Minimum tank: 20 gallons (long) for one adult; add 10 gallons per extra animal
- Temperature: 60–68°F (16–20°C); never above 72°F (22°C)
- pH: 6.5–8.0, with 7.0–7.5 ideal
- Ammonia and nitrite: 0 ppm at all times; nitrate under 20 ppm
- Diet: Earthworms as the staple, plus sinking pellets and frozen foods
The tank: long and shallow beats tall
A single adult needs a minimum 20-gallon long tank. A 40-gallon breeder is ideal for a pair, because axolotls walk on the bottom and rarely use the upper water column — floor space matters far more than depth, and a water depth of 25–35 cm is enough. They are messy eaters that produce a lot of waste, so a larger water volume also gives you more stable temperatures and dilutes ammonia between water changes.
Substrate is a safety decision. Fine sand with a grain size under 1 mm is the usual recommendation, because axolotls swallow substrate particles while feeding and fine sand passes through safely. Coarse gravel is dangerous — it can be swallowed and cause impaction. A bare-bottom tank is also a safe, easy-to-clean option. Avoid pebbles small enough to fit in the axolotl’s mouth.
Place the tank in a cool, quiet spot away from direct sunlight, which causes temperature swings and algae blooms. Axolotls do not need bright light, and a lid is worth having: they can jump, and a lid also slows evaporation.
Water: cycle first, then add the axolotl
This is the step beginners skip, and it is the most important one. A tank must be fully cycled — beneficial bacteria established so they convert toxic ammonia into nitrite and then into less-toxic nitrate — before the axolotl goes in. Cycling takes 4–6 weeks. Adding an axolotl to an uncycled tank exposes it to ammonia, which burns the gills.
- Dechlorinate every water change. Chlorine and chloramine in tap water damage gills. Use a dechlorinator on every change, or age tap water for 24+ hours.
- Test the water. Ammonia and nitrite should always read 0 ppm; nitrate should stay under 20 ppm.
- Change 20–25% of the water weekly. Remove uneaten food within 30 minutes of feeding so it does not rot and spike ammonia.
- Filtration should be strong biologically but gentle in flow. Sponge filters or an external filter with a spray bar work well. Strong currents stress axolotls, which come from still lake water.
Temperature: the single most important parameter
Axolotls are strictly cold-water animals. Aim for 60–68°F (16–20°C), with 60–65°F (16–18°C) ideal. Temperatures above 70°F (21°C) cause chronic stress and suppress the immune system; sustained exposure above 72°F (22°C) promotes bacterial and fungal infections and is often fatal.
Do not use an aquarium heater — axolotls never need one. In a warm climate or a warm room, you will need cooling: a clip-on fan for evaporative cooling works for a few degrees, and an aquarium chiller is the reliable answer if your room regularly exceeds 70°F. Budget for the chiller before you buy the animal, not after a heatwave.
Feeding: earthworms are the staple
Axolotls are obligate carnivores. The best staple food is earthworms — nightcrawlers or red wigglers — because they are nutritionally complete, easy to digest, and readily accepted. Cut large worms into pieces for juveniles.
- Juveniles: feed daily or every other day, in small amounts.
- Adults: feed 2–3 times per week, offering 2–4 earthworms per feeding, until the belly is gently rounded but not distended.
- Supplements: sinking carnivore pellets and frozen bloodworm cubes (especially good for juveniles), plus occasional raw prawn cut into small pieces.
Avoid feeder fish as a staple — they carry parasites and diseases. Never feed mealworms (their chitinous shell is indigestible), mammalian meat, or processed human food. Remove uneaten food promptly.
Tank mates and handling
Axolotls are best housed alone, or with one or two others of similar size in a large tank. Mixed sizes risk nipping: hungry axolotls snap at anything that moves, including a tank mate’s gills or limbs. Fish are not good tank mates — most fish nip gills, and axolotls may eat small fish and pick up their parasites.
Handle axolotls as little as possible. Their skin is delicate and their slime coat protects them from infection; wet hands and a soft container are the only safe way to move one, and only when necessary.
Common problems
- Curled or shrinking gills, loss of appetite: check temperature and ammonia first — these are almost always water problems, not food problems.
- White fluffy patches: usually fungal, and usually a sign the water is too warm or dirty. Fix the water, then seek advice from an exotics vet.
- Floating or trouble staying down: can follow overfeeding or gulping air. Skip a feeding, check water parameters, and watch — persistent floating needs a vet.
- Regrowing limbs: axolotls regrow lost limbs and gill stalks over weeks. A nipped limb is not an emergency by itself, but repeated nipping means the housing needs to change.
Sources
- The Fish Collection — Axolotl Complete Care Guide: https://www.thefishcollection.com/en/species/axolotl
- Herpeton Academy — Axolotl caresheet: https://academy.herpeton.net/en/caresheets/amphibians/ambystoma-mexicanum/
- Tropical Treasures — Axolotl Care Guide: https://tropicaltreasureswyo.com/blogs/tank-buddy-blog/axolotl-care-guide-everything-you-need-to-know
- Reptination — Axolotl Care Guide: https://reptination.com/reptiles/amphibians/axolotl/
- Pet Environment — Axolotl Tank & Care: https://www.petenvironment.com/setup/axolotl