he looks constipated and a little floaty. have you seen him poop lately?
if he did,did it look normal?
has he been eating normally?
how long has this behavior been going on?
have you noticed any other strange behaviors,like gasping/piping at the surface?
i suggest that you withhold food for a few days and then feed blanched,skinned and slightly squished peas.no salt canned green beans or duckweed would work also.