What is the exact "medicated" ingredient in your feed?it ate frozen tiny whiting fish just before the poops started (two days before)...not sure if it was that or the feed at the time.(I changed it to medicated feed next day)..maybe it had mold spores as i hear it can irritate gut also. I suspect it the whiting as the one most affected is the one who ate the most, non stop actually. The others still not showing signs of infection in poop or physically though.