I have these 2 plecos in one tank...a common and a sailfin L001. Some days ther belly is swollen a lot and they want to float on the back half...sitting on the glass tail up...with one fin stuck out sideways. Then somedays they look ok and not sitting funny...then back and forth. Is it some sort of internal parasite? Should I med them....metro or something? They are still eating and everything else seems normal....just bloating and un-bloating. Might have seen some clear stringy poop too....