An axolotl's feathery gills are a display you can read daily, which is why owners spot changes early and then face the hard question: is the water wrong, or is the animal unwell? The honest answer is that gills alone cannot tell you. They shrink, curl and lose fullness for reasons on both sides of that line.
What Gill Changes Look Like
Describe the change in plain physical terms. Gills may look smaller overall, with shorter stalks and fewer or thinner filaments, giving a sparse look against her usual fullness. The stalks may curl forward towards the head, a posture owners often notice during periods of poor water or heat. Filament loss may be uneven, thicker on one side, or paired with colour change, the gills looking paler or duller than their normal tone.
Note whether the skin tells a story too: white or cottony patches, redness, spots, or a slime coat that looks heavier than usual. Photograph her against the glass in the same light every couple of days, so the series shows change a single look cannot prove.
The Water Side of the Evidence
Test on the day you notice the change and write down temperature, ammonia, nitrite and nitrate as figures, not impressions. Compare them with your previous readings if you keep them, because direction matters: ammonia or nitrite showing where they used to read zero, nitrate climbing across weeks, or temperature creeping up during warm weather all belong in the report. Axolotls are cold-water animals, and water sitting above about 68 degrees Fahrenheit, 20 degrees Celsius, is a husbandry fact to report alongside any gill change, hedged by the range your own specialist advises for your setup.
Note recent events with dates as well: a new filter, media rinsed under a tap, a large water change, a dead plant left in the tank, a heat spell in the room, or feeding increased.
The Animal Side of the Evidence
Count who is affected. In a shared tank, several axolotls losing gill fullness together, alongside off readings, is the pattern that points questions towards the water; one animal deteriorating while tankmates flourish in tested, stable water points questions towards that animal. In a single-animal tank there is no comparison group, which makes the readings and the timeline carry more weight and is itself worth saying in your report.
Add feeding and behaviour: meals refused or taken and dropped, floating or trouble staying settled on the bottom, scratching or flashing against objects, hiding through hours when she is usually active. Judge appetite across the week, not from one missed feed; refusal travelling with gill loss and skin change paints a different picture for the vet.
How the Sorting Is Actually Done
The vet or specialist weighs the two evidence sets against each other. Off readings plus group change plus a recent tank event make the water the working suspect, and the response they direct will start there. Clean, stable readings across repeated tests, one animal affected, and signs such as patches, lesions or persistent refusal of food make an animal-level problem the working suspect, and the examination follows the animal instead. Both are working judgements, not verdicts an owner can reach from the glass.
When to Escalate and What to Send
Contact an aquatic vet or specialist promptly if gills are shrinking visibly across days, filaments are breaking down, patches or lesions appear, she stops eating altogether, or tankmates begin showing the same changes. Send the dated gill photographs, today's figures, the comparison with earlier readings, the event list and the animal facts.
Do not start remedies, baths or tank treatments on advice from general forums while you wait; treatments chosen without a diagnosis muddy the water figures and the skin picture the specialist needs to read.
Held in one dated file inside KinsLe, the gill series belonging to Pet Passport sits beside her test results and tank events, letting any specialist scroll from a full, feathery set of gills to today's change without guessing what the water was doing in between.