The effects of introduced tilapias on native biodiversity

The common name 'tilapia' refers to a group of tropical freshwater .sh in the family Cichlidae (Oreochromis, Tilapia, and Sarotherodon spp.) that are indigenous to Africa and the southwestern Middle East. Since the 1930s, tilapias have been intentionally dispersed worldwide for the biological control of aquatic weeds and insects, as bait.sh for certain capture .sheries, for aquaria, and as a food .sh. They have most recently been promoted as an important source of protein that could provide food security for developing countries without the environmental problems associated with terrestrial agriculture. In addition, market demand for tilapia in developed countries such as the United States is growing rapidly. 2. Tilapias are well-suited to aquaculture because they are highly proli.c and tolerant to a range of environmental conditions. They have come to be known as the 'aquatic chicken' because of their potential as an a.ordable, high-yield source of protein that can be easily raised in a range of environments } from subsistence or 'backyard' units to intensive .sh hatcheries. In some countries, particularly in Asia, nearly all of the introduced tilapias produced are consumed domestically; tilapias have contributed to basic food security for such societies. 3. This review indicates that tilapia species are highly invasive and exist under feral conditions in every nation in which they have been cultured or introduced. Thus, the authors have concluded that, despite potential or observed bene.ts to human society, tilapia aquaculture and open-water introductions cannot continue unchecked without further exacerbating damage to native .sh species and biodiversity. Recommendations include restricting tilapia culture to carefully managed, contained ponds, although exclusion is preferred when it is feasible. Research into culture of indigenous species is also recommended.