Hole in Electric Blue Peacock's Stomach - Please Help

Hello,

Yesterday I noticed my 3-4 inch electric blue peacock in a mixed Malawi tank
had what looked like a 1/8 inch bite out of his stomach. The scales were
missing and the area was whitish and he's hiding behind the filter exhaust
at the top of the tank a lot. I figured someone got aggressive and I would
monitor it. This morning I woke up to find the area a little bigger and now
showing some deep red in the center. I moved him to a hospital tank by
himself and he seems to be happier.

Has anyone had this? Do you think it's a bite or some disease? I have been
reading about dropsy and bloat and others and now I am really confused. He's
a beautiful fish that I would love to save but I doubt he'll make it. At
this point I am more concerned with losing more fish if there is a disease
going around my large Malawi tank. I do weekly partials and monitor all my
numbers - all of which are good. I have added some new fish over the past
month but they seem to all get along - aside from the electric blue hap that
sometimes snips.

Any suggestions would be greatly appreciated.

Thank you again!!!
Ross