I think one of my male cherry barb has a parasite. I see a small white thing sticking to his back, just front right side of the dorsal fin. It looks to be pink near the base. He's so quick and it's so small can't see well, but I think it's an anchorworm.
I'm trying to figure out how he caught a parasite (if that's what it is). I haven't introduced any new fish or snails to this tank in a while, but I did feed them extra trumpet snails a few days ago. And it's possible I forgot to wash my hands between tanks and transferred something from the QT or the tenner... Not sure. Have to get a better look at it tomorrow when the full tank lights are on, decide if it needs manual removal (tweezers) or meds to kill the thing.