I have a problem with one of my neon tetras. Two days back, I got a few golden wonder killifish, since I didn't know they prey on small fish and also nobody at the fish store alerted me. Once I put the killis in the tank, one of them went and caught a neon in its mouth. The neon escaped and seemed to be fine, and I quickly removed the killis and returned them. Today I am seeing one of my neons have a greyish patch in the middle of the body. I think it might have been the one that was caught by the killifish and is a healing wound. I would like to know which medication I can use to accelerate wound healing. I am planning to move the fish to quarantine. I don't know if the grey discoloration is infection, but I think it is the wound. None of the other fish have anything like this.
Could you please help.