Let him be if he is eating and acting like nothing is wrong then let his immunity system heal him after all that is why it is there. I use to be a grab the med type person till I saw my husband who is more let the fish heal naturally have better fish that lived longer. I put my fish through hell with medications that killed bio filters or made the fish tired and weak. Do not remove the fish they have been living together see what happens . If he does not seemed bothered then just ignore it and move on. Which I know it is hard you want to move in like Florence Nightengale. Resist....

Yeah, I'm a lot like your husband with the let it be mentality. Due to the sensitivity of the loaches though I wanted to hear someone else say it was ok. (They've gotten pretty big and I wouldn't want anything to happen to them, it'd kill me) Thanks a lot, that's exactly what I needed to hear.