I bought 3 blue (three-spot) gouramis yesterday at Pet Supermarket. The clerk offered to "throw in" a fourth for free, as there were only 4 in the tank and she didn't want to leave him behind. She also said he didn't look so good, and she didn't think "he was going to make it." I said sure! Thanks! I didn't really look too closely at the fish in the bag; they were all pretty stressed so I kept them in the brown paperbag for darkness.
After I put them in the tank, I realized that one of them indeed doesn't look so good. 3 of them are acting normally, but this one seems odd. His body shape is slightly irregular, he's very skinny and almost "bent" looking. His pupils are much larger than his other blue gourami counterparts. So far, he has been spending all his time hovering at the surface, not really moving unless picked on by another fish. This morning, I thought he had died; he was sort of floating around, until some other fish checked him out; then he got back up again (he still kinda swims on his side sometimes, like he can't quite control his rudder). When I fed them last night and this morning, I put hte food right by him, but he ignored it completely (the other 3 gouramis ate well). He just moved out of the way of the other fish.
I'm thinking this probably isn't contagious, but who knows?! Should I allow him to live out his days (which may not last long), or should I try to humanely put him to sleep?
Next time someone offers me a free fish, I'm going to look much more carefully at it!!!