White, cottony fuzz — usually on the gills, toes or a wound — is almost always fungus, and fungus is almost always a symptom of warm or dirty water rather than a random infection. Your first move is to test the water and cool it, not to reach for a treatment. Fix the conditions, keep the animal pristine, and treat the fungus only with methods appropriate to axolotls; get experienced or veterinary help if it spreads or sits on an open wound.
What it looks like
Fungus on an axolotl typically appears as white or greyish, cotton-wool-like tufts. It most often shows up on the feathery gills, on the toes, or on the site of a wound or bite, and it can look fuzzy or stringy. It is different from the normal slightly pale look gills can have at rest — fungus has visible texture, like a small piece of fluff stuck to the animal. If you are seeing genuine cottony growth, treat it as fungus and act, because it can spread.
Why it is really a water problem
Here is the part most beginners miss: fungus is opportunistic. The spores are effectively always present, and a healthy axolotl in cool, clean water fights them off without you ever noticing. Fungus takes hold when the animal is stressed or its immune defenses are down — and the usual reasons for that are warm water, poor water quality, or an injury. That is why chasing the fungus with treatments while ignoring the water is a losing game. The fuzz is the smoke; the water is the fire. Sometimes fungus also settles on an open wound, in which case the wound and the conditions both need addressing.
What to do first
Before any treatment, fix the fundamentals — this alone clears many mild cases:
- Test the water. Ammonia, nitrite, nitrate, pH and temperature. Any ammonia or nitrite, or a warm tank, is very likely the underlying cause.
- Cool the water into range (60–68°F / 16–20°C). Warmth both stresses the animal and favors the fungus.
- Improve cleanliness. Remove waste and uneaten food, do a partial water change without wrecking your filter bacteria, and check that flow is gentle.
- Look for a wound. If the fungus is on an injury, identify what caused it — sharp décor, gravel, a tank mate — and remove that risk.
Treating the fungus itself
If correcting the water does not resolve mild fungus, there are axolotl-appropriate treatments — but they must be used carefully, because this is a delicate amphibian, not a hardy fish. Community methods you will encounter include tea baths or Indian almond leaf, which have mild antibacterial and soothing properties and are sometimes used preventively at the first sign of a wound, and salt baths, which are stronger and used to clear established fungus but can irritate or harm an axolotl if done incorrectly. These methods have specific concentrations, time limits and cautions, and doing them wrong causes harm. Because the details matter and get easily garbled online, follow a careful axolotl-specific protocol or, better, get guidance from an experienced keeper or vet rather than improvising strengths and timings.
When to get help
Escalate to an exotic-animal vet or an experienced rescue if the fungus is spreading despite corrected water, if it sits on a significant open wound, or if it comes alongside other worrying signs — lethargy, redness, sores, refusal to eat or rapid decline. Fungus on its own is treatable; fungus plus systemic signs can indicate something more serious that needs professional care. As always with this species, when you are unsure, the safe move is pristine cool water and qualified advice, not stronger home treatments.