Chunk out of firefish!

[coxy101]

I looked in my tank today and noticed that there's a chunk missing out of my firefish's side! What happened? What should I do?
My inhabitants are:
4'' Fighting conch
Various turbo and nassarious snails
Emerald Crab (never seen him pick on ANYTHING)
4'' Yellow Watchman Goby
2 "mated" firefish (always swim together and have been together for long time)
1.5'' B&W clown
I'm thinking it is the Watchman Goby - he's really defensive of his "cave" and I've seen the firefish sleep down near his cave.
The firefish is acting okay - but it's pretty noticable and I don't want him to get sick... :help:

 

[wocka]

try to post a pic of his battle wound

 

[coxy101]

I don't have a great camera - but I'll try.

 

[ross]

My firefish got a chunk taken out of him too. Just try to keep him as stress free as possible, and feed garlic w/ his food. Thats all i did and he recovered in no time. You shouldn't worry unless he stops eating.

 

[coxy101]

I tried to take a picture but posting it is not worth it. The picture doesn't show the gash really well. His fins are split a little too. He acts fine - I'm just concerned that he'll be more susceptable to an infection. I'll start adding garlic...
Any ideas on "who done it?"