Tilapia (Teleostei: Cichlidae) status in Nicaraguan natural waters

We surveyed the watersheds covering more than 80% of the surface area of Nicaragua, and review the history of deliberate introductions and unintentional invasion of tilapias, Oreochromis spp., into the freshwater of Nicaragua. The species have become widely established, with a range of negative consequences for the rich natural fish fauna of this Central American country. Tilapias compete directly with native cichlids in a number of ways, and have also supplanted native species as food fish in local markets. We suggest that introduced tilapias may have been responsible for the outbreak of blindness in native cichlids. We make recommendations on the management of these exotic species and on further introductions.