Limas.
If it was 24 wide I would say juruense and tigrinus, but for your width limas are likely your best bet.
Depends what youre after really, could go with jaguar cats, gulpers, if you can find one hemisorbim platyrhynchos which I have been after for years but never managed to get.
What are tank mates etc?
Alot of cats can fit in the tank, personaly I would go with limas though.