I have 2 oscars and a pleco in a 55 gallon. My 2 oscars are about 3 inches each and my pleco is about 5 inches. I just got a new tank which is 120 gallons. I think my 2 oscars are a pair. Would it be a bad idea to add a fish or two...and if so what? Maybe a Texas Cichlid or a Jack Dempsey...Any advice would be great thanks!!!