Illness/Sickness: Curled gills on my axolotl

[appshan]

Hi, everyone! I have a wild-type axolotl. His gills were pretty straight in the last picture (when I first got him). Now, his gills are curled (see first and second pictures). The first picture was taken yesterday after he had been living in a 16qt tub for a couple of days. The middle picture was taken a few weeks ago, when he was living in a 6qt tub. Also, his tank has a natural pothos plant and a ceramic log -but he never uses it to hide. Should I be worried about the curled gills? Or are they getting curled since he is getting bigger?

 

[wolfen]

at the moment it looks like the gills are drawn forward due to size and fullness rather than due to stress.

 

[appshan]

at the moment it looks like the gills are drawn forward due to size and fullness rather than due to stress.

Thanks!