i would get a RTC but you already have a catfish though so i would say an oscar cause i have a pacu 2 oscars a Redtail catfish and an Alligator Gar and then seem to get along great so maybe try one of those? good luck buddy
I live in florida with a 3,000 gallon pond and I need very little heating!!!!! Come on guys I just wanna know what fish are compatable.