I have a coral beauty angel that had a small split in his dorsal fin when I purchased him a month or so ago. It has gradually increased to the point where it is a patch of white skin(open wound).

I went to Alamo Aquatics to discuss wehat could be done. Taking him out of the tank is not an option as he is fast as lightening. They recomended treating the tank with melfix or ethromicyn(I know I might have these names spelled wrong). Have any of you used these items, and would you dose the tank? I am worried about everything else in there.

Blue Throat Trigger
Pink spotted Gobie
3x firefish
Clown
Purple Lobster
Engineer Gobie
Some SPS, LPS, Zoas, and my giant finger leather

Let me know, Thanks!