Today I decided to purchase a guppy to go along with my female betta and three platys. The betta has chased the other fish before, been houses with guppies, but has never "attacked" another fish, so I didn't see much issue with adding a single guppy. The guppy I purchased did a fun slit and while he was in a bag to be brought to my home, roughly two hours, the yellow on his tail started turning white. Did a WC, checked my females behavior and put the guppy in. Everything seemed fine, but over the next few hours the guppy began to display troubling behavior; trembling, his tail literally falling apart, staying in the same area, etc. I did see my betta being a bit more aggressive than usual, a female platy appeared to have a fin tear, but that doesn't explain the earlier issues with the guppy. I checked water parameters, everything's normal bar temperature. My temp is currently 86 degrees as I'm on the last few days of ich treatment. I have been using aqua salt after using Nox-Ich; but again, a water change of some 70 percent was preformed. Confused as to what's going on. Thanks! Also sorry for any typos, I'm dead tired and rather worried I inadvertently killed the poor thing.