don't know whats wrong

Hello all! I have had my betta fish since August of ‘19. He has handled a few different moves since then very well. I went away for a few days and when I got back I’ve noticed he isn’t swimming or nearly as active as he use to be and he is either found resting on his side on the bottom or in his...

Okay, so last night I decided on buying another betta when I had went into my local Petco. (normally i would not buy from there because they don't take very good care of any of their fish) I tried my best to spot if he was already sick and all, and he seemed very active then, but just a bit...