All of us are fascinated by cichlids, and probably by their diversity and the sheer number of species and variations on the theme cichlids. At one time or another we have probably wondered where they came from, how did they get to where they are, and how come there are so many different species?

With this article I will attempt to give some ideas on how to solve the riddle that is cichlids.

Tropheus moorii "Mbita" of Lake Tanganyikais a highly specialized algae grazing cichlid

Cichlids are secondary freshwater fish. That means that they derived from seawater fish that again populated the freshwater. This has one great advantage over other species whose ancestors never went back to the sea: secondary freshwater fish have a much higher tolerance for salt than primary freshwater fish, therefore giving them an advantage in colonising waters that are high in dissolved minerals.

The first cichlids probably inhabited the rivers of Africa, where we still find some species today. A long time ago the Great African Rift cut through the Congo River, and the waters of the inflowing of what is today the Malaragasi River were trapped and formed Lake Tanganyika. The water became stagnant and was warmed by sun as well as geothermal ...