Jacks might work but it would be a bit tight, you would likely need a growout tank. Severums could work as well but like the JDs it would be tight. How about firemouths?
As for catfish, bushynose plecos are your best bet. Those or corydoras.
Madtoms are good catfish. Or you could try some of the hillstream loaches that have been bred, such as Pseudogastromyzon cheni, but like everyone else said, bushynose plecos would probably be your best bet. You could also try green terrors, jewel cichlids, or a smaller pike cichlid species. You could also try some yellow labs or other mbunas. There are also firemouths and Honduran red points(either a different kind of convict or something closely related), which get much prettier than convicts.
