Mbuna (pronounced boo-nuh ) is the common name for a large group of African haplochromine cichlids from Lake Malawi. The name mbuna means "rockfish" in the language of the Tonga people of Malawi. As the name implies, most mbuna are cichlids that live among the piles of rocks and along the rocky shores of Lake Malawi, as opposed to the utaka and other "haps", cichlids that live in the open water or on sandy shores or soft substrates. Some species of mbuna are highly sexually dimorphic, although many are not. Among biologists, all of the cichlid species of Lake Malawi, including mbuna and nonmbuna such as the utaka, are believed to have descended from one or a very few species that became cut off from each other through periods of decreasing water levels that formed the three Great Rift lakes into many smaller lakes. In isolation, they became adapted to their immediate surroundings. With time, the waters again rose, and these new species now became adapted again to new environments and new competition. The introduction of these, now highly specialized species to each other, resulted in many strange adaptations and unique behaviors, making them some of the most unusual freshwater fish in the world. Their striking colors, intriguing behavioral characteristics, and relative hardiness make them very popular despite their unique demands for the home aquarist.