Racf wrote:

I rather doubt that they feed ONLY on algae. I imagine they may feed
mostly on algae due to lack of anything else..... Oscars will eat
algae, if thats all there is to eat... I have read many times over the
years that high protein diets will kill Mbunas, but I never really
believed it. I guess its possible...I just never bought in to it. Fish
will eat about anything they can get...in the wild or in the tank....In
the wild specialization would tend to favor certain species in certain
situations....If all there was to eat was buffalo chips, I imagine
anyone that liked them woud do quite well....while the rest of us would
end up eating each other...

You obviously aren't a biologist otherwise you'd know how preposterous the
claim that they eat algae because of a "lack of anything else" is. The
algae eating cichlids of the rift lakes are morphologically and
physiologically adapted for the primary ingestion of algae.

The dentition of the upper and lower jaws has adapted to a form more
suitable for scraping algae off rocks than catching prey, usually bi- or
tri-cuspid teeth. The pharyngeal jaw apparatus is similarly evolved for
the processing of algae matter (as opposed to fish or snails). If you can
find it, "The Cichlid Fishes of the Great Lakes of Africa" by Fryer and
Iles is an old, but good reference on the morphology of rift lake
cichlids. It has illustrations that will show the differences in jaw
structures as well as a whole chapter explaining how the various feeding
mechanisms have evolved specialized dentition for that feeding mechanism.
That chapter also mentions how some algae eaters take specialized care to
exclude even accidently eating invertebrates with its algae.

The mbuna also have an intestinal tract adapted to digest primarily
vegetable matter. This means the tract is long. The occasional
invertebrate inadvertantly caught with the algae will not upset the
intestinal tract to a great deal, but a primarily meat diet will. Just
because the fish will eat it when presented with the food doesn't mean
they can digest it. They are not carnivores nor omnivores. They are
herbavores. You must feed them a diet appropriate to their physiology and
morphology if you expect them to live a long and healthy life.