SUCCESS THROUGH DIVERSITY AND CARVING OUT A NICHE: THE EXAMPLE OF CICHLIDS

One of the most diverse of families in the Animal Kingdom is the family of Cichlids fishes. There are estimated to be 2600 species of Cichlids, and each year more are discovered.Each of the narrow , deep lakes of the African Rift Valley (lakes Malawi, Tanganyika and Nyasa),contain more than a thousand species of Cichlids. There are also Cichlids in South America and a few species in Asia. 

Through evolutionary adaptation, each species carves out a niche for itself in the micro-ecosystem that it occupies.. Thus species of many shapes, colors, kinds of diet and mating behavior have evolved to suit the characteristics of each niche in the ecosystem. Fast-flowing/slow-flowing waters, acidic,alkaline, brackish, environments with many predators, low-oxygen etc there will be a Cichlid that is able to thrive. You might find it interesting to know that the Discus and the Angel Fish despite their very different shapes, belong to the Cichlid family. So is the common Tilapia that we eat.
One aspect of successful adaptation is: Mating habits. Depending on the micro-environment, Cichlids can be monogamous ( one male, one female for life) polygamous ( one male and a harem of females) polyandrous ( one male, many females) or simply promiscuous ( free-for all orgy). But they all gave one thing in common: they practice good parenting , both male and female playing their part to ensure the young survive through the vulnerable earlier days.
Photo shows a collection of various Cichlid species collected from one lake- Lake Okeechobee in Florida. Though not even their native waters, there are estimated to be 44 species of Cichlids in the lake, all derived from escaped aquarium fish or those introduced to perform algae-eating or pest control function; which shows how adaptable they are.