My mandarin seems to be struggling, first he ate all the Pods
in my tank, and has been forced to eat some frozen food which I think initially hurt him. But now he's got 1 single white HOLE on his back. thats right a hole, maybe 1/3rd of an inch in diameter, and maybe a couple cm deep. What the hell could this be? None of my other fish show any stress at all, and this guy has a fairly developed hole???