I have a 6 female sorority tank. 5 are acting normal but one was floating at the top when I woke up this morning, she’s sunk to the bottom and floated back to the top a few times. She wound up floating up against the glass and I see a white poop attached between her fins. She’s also having 2-5 second bursts of erratic swimming. At first I was just going to fast her, thinking she over ate. But now I’m thinking of medicating. I don’t know if it’s too early or if I should do it before things get worse. And should I quarantine her at this point or should I be treating the whole tank??