I agree that an Oscar gets too big for a 55g. The most interactive and entertaining fish for that size tank IMO that's on your list is a pair of Severum.
I have an even better suggestion though. If I were you, I would make it a single cichlid, male Green Terror tank. It's a very beautiful, responsive and aggressive fish that makes an awesome wet pet. GL.
I have an even better suggestion though. If I were you, I would make it a single cichlid, male Green Terror tank. It's a very beautiful, responsive and aggressive fish that makes an awesome wet pet. GL.