pygmy anglefish missing tail

[freewilly2]

I just noticed while feeding tonight that my pygmy anglefish looks like pieces of its tail have been picked off. The craziest thing is that it is the only fish in the tank righ tnow along with an arrow crab. could this be the work of an arrow crab or is this a disease that needs to be treated.

 

[Fiver]

Get that crab out.

 

[Jdub968]

Could be the crab if the fin looks as though it has had a piece nipped out of it then the fish should be fine it's when the fins are tattered and the entire
Fine is like an old flag that's been blowing in the wind, this generally suggest a bacterial infection