new fish suggestions

I have a 55 gallon aquarium with 2 angle fish that aren’t a breeding pair and 4 corey catfish. What should I add to the tank. I had the tank now for about a year.

Currently I have 5 golden Kelberi Bass ranging from 6"-8" in length. They're housed in a 1000 gallon aquarium with lots of plastic plants and hiding spots in the tank. Their only other tankmates are an Oscar about 7", a Green Severum around 11", a Managuense around 13", a Endlicheri around 18"...