I got three pink anthias about a week ago, they all looked happy but one of them would not school with the other two. The three have been eating well but I just noticed today that one of them(probably the one that didnt school with the other two) appears to have a injury on the side.

Here's a pic:



What could have happened? I also have a pair of clownfish and a lionfish in the tank but I have never seen anyone fighting.

Thanks,

Jose