Test the water before you change the food
When an axolotl that normally eats well suddenly refuses, the water is the first suspect, and the first tests are ammonia and nitrite. Both should read zero in a settled tank; even a small reading of either irritates an axolotl's gills and skin and commonly kills its appetite before any other sign appears. Nitrate is worth checking too, since high levels from overdue water changes add to the stress. Use a liquid test kit rather than a dip strip, because the decision you are making needs a trustworthy number, not a rough colour guess. Nitrate rarely explains a sudden refusal on its own, but a high reading alongside any ammonia at all paints the picture of a tank whose maintenance has slipped, which is usually the real story.
Check the temperature alongside the chemistry
Axolotls are cold-water animals, and water that has crept up through a warm spell, a hot room, or a failing fan can push them off food on its own. They do best in the high teens in Celsius — the low sixties in Fahrenheit — and sustained warmth above that range suppresses appetite and weakens their resistance to infection. If the tank has warmed, cooling it gradually and safely matters as much as any water change; sudden swings in either direction are a stress of their own.
Then review what changed in the last few days
Water quality rarely falls without a cause, so walk back through the recent history: a skipped water change, uneaten worms left to decay in a corner, a filter rinsed under the tap or switched off, a new decoration, or a well-meant but oversized water change that disturbed the cycle. Each of these can explain a sudden ammonia rise or a shift in acidity, and finding the cause is what stops the same refusal happening again next week. Check, too, that the filter is actually running and its flow has not stalled.
Correct gently, then offer food again
Fix what the tests show with partial water changes using dechlorinated water matched to the tank's temperature, remove any decaying food, and let the readings settle before offering a favourite food again. Many axolotls resume eating within a day or two of the water coming right. If yours does not, or if you see gills curled forward, a thinning body, skin lesions, or floating it cannot correct, that is the point to contact a veterinarian who treats amphibians — appetite loss that survives clean, cool water is no longer a water question. While the water settles, watch the axolotl rather than the calendar: gills held feathery and open, a willingness to stalk a wriggling earthworm, and a body that still looks full behind the head are the signs the tank fix has done its work.
Keeping each test result alongside the change you made in response turns a worrying evening into a pattern you can actually read. KinsLe's Pet Passport keeps those water records in your axolotl's own packet, ready to hand to the vet if a home check ever needs to become a consultation.