Axolotl Tank Setup: Cold Water and No Gravel
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Axolotl husbandry comes down to a short list of rules that matter a lot: keep the water cold, skip the gravel, and don't overthink the rest. Get those two things right and this is a genuinely manageable pet.
Tank Size
A 20-gallon long tank is the minimum for one axolotl, with a 40-gallon breeder better if you're keeping two. Two axolotls in one tank will bite at limbs and gills, especially at feeding time or when sizes are mismatched, so housing separately is the safer default. Juveniles are known for cannibalism, so young axolotls are raised apart, and adults share a tank only with plenty of space. Floor space matters more than height for this bottom-dwelling species. Use a secure lid, axolotls are capable of climbing out given the chance.
Water Temperature: The Defining Requirement
Keep the water between 60 and 64°F. Above 72°F starts to cause chronic stress, and it can become fatal in the mid-70s. Do not use a heater. Instead, plan for an aquarium chiller (or the 1/10 HP titanium-coil chiller for a smaller tank) or, in cooler climates, fan-based cooling to keep temperatures in range, especially through warm months. A reliable water thermometer makes it easy to catch drift before it becomes a problem. Keep the tank in the coolest room available, away from windows and heat sources, which does part of the chiller's work for free.
Sizing a Chiller Against the Tank
A chiller is sold by the volume of water it can cool, and that rating comes with conditions attached. Hailea, for example, rates its HC-150A at 150 liters (about 40 gallons) and its HC-300A at 300 liters (about 80 gallons), and states that those figures were calculated in a 30°C (86°F) room with the water starting at 28°C. A chiller's rated volume is the most it can handle under those test conditions, not a comfortable working load.
So size by the whole system, not just the tank label. Add the water in the filter and any sump to the tank's volume, then pick a unit whose rating sits well above that total. A 20-gallon long holding about 20 gallons sits comfortably inside a 40 gallon rating; a 40-gallon breeder is already at that unit's limit and belongs on the next size up. Go up a size again if the room regularly runs hotter than the 86°F the rating assumes.
A chiller also needs water pumped through it, and axolotls are extremely sensitive to current, so bring the return back through a spray bar or into a baffled corner.
Water Parameters
Ammonia and nitrite should both read 0, nitrate should stay low, ideally under 10 ppm, and pH should sit at 7.4 to 7.6, with 6.5 to 8.0 tolerated as long as it stays stable. Check these with a water test kit. The tank needs to be fully cycled before an axolotl goes in, this isn't a species that tolerates an uncycled tank while it establishes itself. Change 20 to 30% of the water every week with dechlorinated water, which keeps nitrate down between tests. Each of those readings maps to a stage of the nitrogen cycle that keeps axolotl water cold and clean.
Axolotls never go through the land-based metamorphosis most salamanders do, they keep their gills and stay fully aquatic for their entire lives. That's exactly why nothing in a proper axolotl setup, unlike a lot of other amphibian tanks, needs a land area or a basking spot at all.
Substrate: The Other Non-Negotiable Rule
Use fine sand with grains under 1mm, or skip substrate entirely and go bare-bottom. Never use gravel or small rocks. Axolotls are opportunistic eaters and will ingest loose substrate along with their food, and anything larger than fine sand carries a real impaction risk. Keep juveniles under 5 inches on a bare-bottom tank until they're larger and less prone to accidental ingestion.
Filtration
Use low flow. Axolotls dislike current and can become stressed by filters designed for more active fish. A gentle sponge filter or a canister filter with the output diffused through a spray bar both work well.
Diet
Earthworms or nightcrawlers, cut into appropriate sizes for juveniles, are the nutritionally complete staple. Sinking pellets (salmon-based or invertebrate-formulated options) work as a supplement, and bloodworms make a good occasional treat. Adults eat every 2 to 3 days, juveniles daily.
A Few Other Details
Keep lighting dim, axolotls don't have eyelids and are sensitive to bright light. Put the light on a timer for a 12-hour day, so the tank goes fully dark at night. Provide hides for security. And keep the tank species-only, axolotls don't do well housed with fish, which can nip at their gills or outcompete them for food.
Once this setup is in place, day-to-day handling should stay minimal. The Axolotl encyclopedia profile has more on the species.
Gills are only part of how one breathes, since it uses skin and simple lungs as well, which the axolotl Beastfile explains.
Sources & Further Reading
Last reviewed 18 Jul 2026 · 5 sources
The Axolotl Care Package carries this setup as a checklist with the targets to hit, in a 46-page PDF you can keep by the tank, $8.99.
Frequently Asked Questions
What size tank does an axolotl need?
A 20-gallon long for one, and a 40-gallon breeder if you keep two, though axolotls bite at each other's limbs and gills, so housing separately is the safer default. Floor space counts for more than height with a bottom-dweller. Use a secure lid: they can climb out given the chance.
What temperature should axolotl water be kept at?
Between 60 and 64°F. Don't use a heater, plan for a chiller or, in cooler climates, fan-based cooling instead. Above 72°F starts to cause chronic stress, and temperatures in the mid-70s can be fatal.
What substrate is safe for an axolotl tank?
Fine sand under 1mm, or nothing at all. Gravel and small rocks are out: axolotls swallow loose substrate with their food, and anything bigger than fine sand carries a real impaction risk.
What do axolotls eat?
Earthworms or nightcrawlers as the staple, since they are nutritionally complete, cut down for juveniles. Sinking pellets supplement that, bloodworms are an occasional treat. Feed adults every 2 to 3 days and juveniles daily.
More on the Axolotl
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Written by Michael Ryan
Mike keeps two rescued bearded dragons, Dex and Cera, and writes the care guides on BeastlyFacts from his own research and mistakes. He is not a veterinarian.
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