Wow that's a crazy stocking in such a small tank. You need to upgrade now or start to rehome. Tank is only big enough for one of those oscars at any size. You should always stock a tank for the final size of the occupants to be. Your headed for disaster within days or weeks. Your fish are without a doubt suffering right now from stress. Impossible for them not to. Who told you that you could stock all these in a small tank and some that should never be together? I would make sure to never listen to them again. Do some research and get yourself going in the right direction early instead of dealing with problems later, and making the fish suffer for it.