Axolotl Gill yellowing and shrinking

[Animal mom]

Ok I’ve searched every thread looking for something similar and haven’t found it so I’m asking here! My baby is about a year old, fully cycled tank, always had beautiful big gills, overnight one Gill started yellowing and has been shriveling. Recently added another Axolotl to tank, same size, both males. It doesn’t look like fungus to me, maybe an injury? Anyone have some input? Thank u in advance!

 

[Dr. Phil]

I think you may be right about an injury and I would suspect his tank mate. You may wish to try putting a tank divider in there to keep them separate.