Axolotl care guide: tank, temperature, substrate and diet

Temperature is the thing that kills axolotls

If you remember one thing, make it this. Axolotls (Ambystoma mexicanum) are cold-water animals from high-altitude lakes in Mexico. Their ideal range is 16-18C (60-64F), and they tolerate up to around 20C. Push past 22-24C and they go off their food, their slime coat suffers, fungal and bacterial infections set in, and prolonged heat is simply fatal.

This means no heater - the opposite of a tropical tank. In a cool room you may need nothing. In a warm room or a hot climate, keeping the water cold is the real challenge and may require an aquarium chiller, or at least a clip-on fan blowing across the surface and frozen water bottles in a pinch. Be honest with yourself about your room temperature before buying an axolotl - this is where most go wrong.

The substrate rule: bare bottom or fine sand

Axolotls feed by creating suction, vacuuming up food and anything sitting near it. Give them gravel or small stones and they will swallow it, and swallowed gravel causes impaction - a blockage of the gut that is frequently fatal and hard to treat.

So the only safe choices are:

• Bare glass bottom - safest of all, easiest to keep clean, and fine for the animal even if it looks plain.
• Fine aquarium sand - looks natural, gives them grip (they slip on bare glass), and passes harmlessly through the gut if a little is swallowed.

Never use gravel, pebbles, or small decorative stones in an axolotl tank. See our substrate options guide for how sand compares to other choices.

Tank size and setup

• Size: at least 75 L (20 US gallons) for a single adult; they grow to 20-30 cm. Floor space beats height - they are bottom-dwellers - so choose a long, wide tank.
• Filtration: they are messy, so you need good filtration, but they dislike strong flow. A sponge filter or a baffled hang-on-back/canister is ideal. Strong current stresses them and can curl their gills forward.
• Hides and cover: provide caves, plants (real or silk) and shade. Axolotls have no eyelids and dislike bright light, so keep lighting dim and give them somewhere to retreat.
• Lid: keep it covered - they can and do climb or jump out.

Water quality and parameters

Axolotls have permeable skin and delicate external gills, so they are sensitive to poor water - in some ways more so than fish. The tank must be fully cycled before they go in, and the water dechlorinated.

• Ammonia 0, nitrite 0 - non-negotiable; both are highly toxic to them.
• Nitrate low - keep it modest with regular water changes (roughly 20% weekly is a good starting habit).
• pH 7.4-7.6 - neutral to slightly alkaline.
• Moderate hardness - very soft water is not ideal; a little mineral content keeps them healthy.

Use a liquid test kit and stay on top of it, especially while the tank is young.

Diet

Axolotls are pure carnivores. Good staples:

• Earthworms / nightcrawlers - the gold-standard staple; nutritious and well digested. Cut to size for smaller animals.
• Sinking carnivore or axolotl pellets - convenient and balanced.
• Bloodworms and blackworms - good supplements, especially for juveniles.

Avoid feeder fish. They carry parasites and disease, can introduce thiaminase, and pose a choking risk. Feed adults every 2-3 days and juveniles daily, and remove anything uneaten to protect water quality.

Tankmates: keep it simple

The honest answer is that axolotls do best alone. They will eat any fish small enough to fit in their mouth, and fish - even small ones - peck at their feathery gills, causing injury and infection. If you want more than one axolotl, keep them at a similar size in a tank large enough for each, and watch juveniles closely, as young axolotls will nip each other's limbs and gills (limbs regenerate, but it is still stress and infection risk).

Related guides

• The nitrogen cycle (cycle before adding livestock)
• Understanding water parameters
• Aquarium substrate options
• When your tank is too warm