Weird Poop

[mommyof2bettas]

I was just over at Wal-Mart and came back with a rescue betta-he had the worst tattered fins out of all the others. Now, most of the other bettas there (he's not one of them) had green poop... and it was floating I know it was poop cuz I saw a couple pooping it out. I heard with internal bacteria the poop is white and stringy... would this just be a different kind of internal bacteria, or something else? Thanks i\for any answers