live food?

I was wondering if there is a live food I could feed to my cichlids as
a treat? I have a 55 gallon tank with about 15 cichlids at about 3 or
4 inches long.I feed them cichlid flakes,african sinking pellets or
staple floating type pellets rotating them every couple of days so
each is happy.Every once and awile as a treat I offer them krill
crumbleing it for them.They love it.I have tried to make the tank
enviroment as natural as possible with many stones arranged as caves
and real plants that most seem to play and hide in and around and a
couple of others that stop at nothing to pull each plant up.I'm new at
this and have had this tank for about a year.I guess becouse I want it
as natural as possible I wonder often what most (wild) cichlids
eat.Most of mine are african with a couple of jack
dempseys,convicts,electric yellow,electric blue and a 5 or 6 inch
algae eater to help clean up.Thanks for any advice.