For jags you could go with an Oscar or green terror any other cichlids around the size of a jag cichlid. Personally I kept sevs with jack demspeys before (might be because they were introduced to each other as juvies). If you find cichlids around the same size, same personality, and same region it lives in it should work most of the time. It could be a hit or miss with cichlids, some might get along and some might not. It's just a matter of luck.