Pictus catfish tankmates?

I have one almost full grown pictus catfish. He has always been alone and I wondered if he would like having another one or two of his kind since they're supposed to be schooling fish. Would he be aggressive towards other pictus catfish since he has always been alone? Also, what type of schooling fish that are top feeding fish could I include in the tank? It's a 20 gallon. And there are plenty of hiding spots for my catfish, JoJo.�They are bottom feeders.�