The redbelly tilapia, also known as the Zille's redbreast tilapia or St. Peter's fish, is a species of fish in the cichlid family. This fish is found widely in fresh and brackish waters in the northern half of Africa and the Middle East. Elsewhere in Africa, Asia, Australia and North America, it has been introduced as a food fish or as a control of aquatic vegetation. Where introduced, it sometimes becomes invasive, threatening the local ecology and species. The redbelly tilapia is an important food fish and sometimes aquacultured.

Tilapia is the common name for nearly a hundred species of cichlid fish from the coelotilapine, coptodonine, heterotilapine, oreochromine, pelmatolapiine, and tilapiine tribes, with the economically most important species placed in the Coptodonini and Oreochromini. Tilapia are mainly freshwater fish inhabiting shallow streams, ponds, rivers, and lakes, and less commonly found living in brackish water. Historically, they have been of major importance in artisanal fishing in Africa, and they are of increasing importance in aquaculture and aquaponics. Tilapia can become a problematic invasive species in new warm-water habitats such as Australia, whether deliberately or accidentally introduced, but generally not in temperate climates due to their inability to survive in cold water.