They are semi-easy to care for - they are territorial so in a 40 litre tank I wouldn't have more than 2 or 3 at most. They also prefer live food over dried food, so unless you somehow get some already conditioned to dried you will rarely see them going for flake or bottom feeder food etc. Mine have been going for it rarely and only in the last few weeks.
The males are the ones with colours, I don't know how they behave when there are females, probably a bit more aggressive from male to male, but I've never seen the females available anyway. They'd probably be quite good with pygmies, they are compatible sizes anyway.