I moved my kuhli into my fry tank a few days ago (dont mind the ugly gravel) after the other two died in the main tank from ich meds. Today I noticed that his tail was mangled and it looks like it’s dorsal fin is gone. While i was moving this guy into the fry tank, I noticed it had a red dot on its side. Could this be fin rot? Would a 2 month platy be able to do this? Or a pair of rams or adult platys? I added pimafix but idk what else to do, he’s struggling to swim. Last picture with black sand is from when it was living in the main tank a few days ago. 
