One of my recent imports I've kept in QT has white poop. She didn't when she first got here, and has been in the same tank the whole time. The poops are not white and stringy, they look like regular poops but just white. Ie kind of lumpy and irregular - lol sorry this is gross.
Anyway, she's eating and looks fine, not clamped or anything, in a 1/4 gallon hospital tank floating in the sorority so it's heated, water changes every day with pellets and no substrate or anything. Really glad I kept her separate.
Today she pooped the normal reddish-brown color of her pellets but it had a bit of a yellowy see through end.