I would say either the puffer or the female maroon they are more aggressive and if they have pick a new territory they will defend it to the death. That is just the way they are almost and clown is that way but especially maroons, I have 2 medium sized perculas that will bite me if my hand is in the tank longer than they like it to be. Momma has taken small bite out of my hand, I think she had laid eggs some where near there or some thing it was near their Nem so that could have been why also. I can put my have near the Nem for a while but then after that short time that is that she is no me like flies to honey.

To help with the tail try adding some melifix as per directions on the bottle it should help promote groth and prevent an infection. Marine fish when injered are prone to infection and fungus rot of the fins when they have been injered.

Bill