I have a tank with a lawnmower blenny, midnight dwarf angel, and two ocelleris clowns (all juvenile). I had been looking to add a pair of damsels as the final fish to the tank. A couple days ago I saw a pair of pink and yellow ones at my LFS that were very healthy and a great price so I brought them home. Their acclimation to the tank went very well, and they soon established their area and were doing great. Then today I noticed that one of them had been what appears to be bitten at the cranial base of its anal fin. There is a chunk missing and the area is very blood shot and inflammed. The damsel is currently in my 10g hosp tank being treated with Melafix. My question is whether or not this is actually a bite or if he possibly hurt himself on the live rock, and what the best way to treat would be. He is acting noramlly, swimming fine, and has a very healthy appetite for both flakes and frozen. All other fish seem fine.