In my experience with central american cichlids, I learned that they love eating all the weird kinds of algae that other fish will refuse to eat. I had a cutteri pair that would gorge themselves on filamentous algae, and all my convicts eat cyano. It's a funny sight to see a one inch convict ripping a giant sheet of cyano off a rock and slurping it down like spaghetti. I also have an f3 labiatus that likes salvinia more than gambusia.