What is this?

[benjaminspades]

Why is my fish's fins receding? What's going on?

 

[triggreef]

Who are his tank mates? Happening to others or just him?

 

[benjaminspades]

Happening to just him. which is very odd? There is a super male mccoskers, a black ice clown, strawberry crab, one firefish, and a big pink spotted goby. that's it pretty much