Great idea, many catfish have not been bred in captivity yet but get a group of what ever you like and start playing around with diet, temperature changes, water changes/water levels (things like doing a change with cool water and using a watering can to simulate rain, or lowering the water level and increasing temperature) etc. and see what you can achieve. I have heard of Australian natives being excited into spawnnig by the fact they were being photographed and thing the flashes were lightning, signaling rain in the wild ! Make sure you post the results here. If you are after a smaller predator I would try smaller asian bagrids like mystus or asian bumblebees, pictus or bumblebees from SA, maybe some Tanganyikan bagrids (phylomenis ?) or even North American natives. Good luck.
Cheers,
Ken
