as they get to 6inchs<usually smaller you quite limited really, they need to be kept in large groups,this brings them out of there shells and you will find they will eat happier in a group, also good plant cover is needed with these guys esp floating plants..
for a group i would say atleast 6
Have a look at debauwi catfish, a pretty cool little catfish, again needs a group
I would say you could try things like festivum cichlids, kribensis, half banded eels, senegal birchirs, other than this youe quite limited,