Death of axolotl

Five weeks ago I purchased a speckled grey axolotyl for my daughter using a 3 foot long tank, say 130 litres, a fluval U4 internal filter set for the water surface rippling only. From what I have read on your site it appears to be a female and has seemingly done quite nicely. At the four week mark, last Saturday I purchased an albino, and it appeared to be a male. On introducing him to the tank he completely covered the female and then left her alone after the second day. Both are around 6 to 8 inches in length. On Wednesday, day 5, we we found the albino dead in the bottom of the tank and had completely turned a red hue or dark pink. The original axolotl is doing quite fine. I checked ammonia levels and they are almost negligible. pH is at 7.4. Temperature is a constant room temperature of 19 celsius. What could have caused this when the other is doing quite fine?

I'm very sorry for your loss

However, did you isolate the new axolotl before introducing him to the tank? Sometimes newly bought axolotls can harbour diseases which become apparent when they are stressed.

Have you tested for Nitrite and Nitrate levels? Your female may be used to the tank conditions and if they turn out to be higher than would be expected, it might be that they were too much of a leap for him. Stress is also a causal factor - they get very easily stressed, especially when moving.

The red hue might indicate burns (from Nitrite or Nitrate, as you've ascertained ammonia is not the cause) or possibly a bacterial infection which, combined with the stress of moving, caused him to pass on. If he was bloated, especially around the head, this may indicate death from a bacterial infection or possibly organ failure - which would explain why your older axolotl is fine. Can I just ask what kind of test you used for your ammonia? If it was a strip test you may want to try a liquid test instead, as the strips aren't meant to be that reliable.

I would keep an eye on your first axolotl to be sure it's not contagious, and if you see any signs of illness (unusual levels of movement or stillness, fungus, ich, sudden and rapid change in colour, etc) I would suggest getting her to a vet ASAP. It may not be all that dramatic, though, and your poor second axolotl may simply have been poorly for a while or had something genetically wrong with him.

I hope your first baby is okay!