I do the same...It is a life saver for big catfish. Some people buy tilapia and shrimp, I catch bluegill and perch and carp and bullheads. Its free and the fish love it. I see no problem with it just as long as you're responsible about it and are not wasteful and let the really big ones go to reproduce. I also freeze them for atleast a month before I feed them to the fish just to be safe. Also, In my experience, yellow perch can get loads of parasites during the summer and are probably best caught during the spring or winter although I doubt it matters if you freeze them. Just don't be surprised if you see black dots all over the perch.
As for temperature, I have no idea but obviously the colder the better.
As for temperature, I have no idea but obviously the colder the better.
