About 4 days ago I got 2 pbass that are about 2 inches in length. They were in a tank with two oscars and two rosy reds.. The rosies are about a month old because nobody wants to eat them and they are getting very big after scavenging anything that falls into the tank. It looked like the rosies were giving the pbass a hard time (going after them, stealing food) despite the pbass being larger so I took out the rosies and gave them some live brine shrimp and after a little I noticed that the two bass were fighting each other. The fish are virtually the same size but it actually looked like the one that was a tiny bit smaller was the one doing the bullying. The other bass has a ripped back dorsal fin now and when I went to feed them a little to later to see what would happen the one bass stayed hidden inside of a log while the other one ate. Should I separate them? Will this pass? Could the oscar and pbass ever fight? Also one of the oscars started to look sick 2 days ago so I separated him and it looked like he suffered from an internal parasite and just died last night in the quarantine tank, any chance that my other fish could be/eventually suffer from this just from being around him? As far as live food is concerned, I have another tank set up with guppies in it and if I were to feed them fish flakes and leave them in there for a week would it be safe to feed them to my bass? Thanks!