A green terror, salvini, or medium sized (8-12 inch) pike cichlids would work well, any medium sized cichlid really.
Another fish you could get could be a type of sunfish (red breasted, green, pumpkin seed, warmouth, rock bass, bluegill, etc.). Make sure it's legal to keep them in your area
Do you have a preference for anything specific?
Like community or just a single fish?
What about region like African, South American, Central?
Planted, Brackish, Saltwater?
Edit: I just saw in another thread you had a Dat,
Do you still have this fish?