I bought three chromis fish. The next morning this one looked like it had a big gash on it's side that was previously not there. I did not use a net, nor did the LFS. Any ideas what it was? It took about a week to do it in, I gave it garlic, no help. All the tests are fine on the tank and I added a goby 3 days ago which is fine, the other two chromis are fine too with no problems.
