Titicaca Orestias

Known locally as the amanto, the Titicaca Orestias is a freshwater fish that once lived in the high-altitude waters of the South American Altiplano. This species belongs to a group of killfish found in isolated basins across the Andean highlands. Measuring up to 27 cm in total length, it was the largest member of its genus. It was distinguished by a flat head with a concave, dish shape and a lower jaw that was black. Its body was greenish-yellow to umber on top, while the scales of adults were granulated with light-colored centers.

These fish lived in Lake Titicaca, a massive body of water on the border of Bolivia and Peru. In this closed environment, the Titicaca Orestias functioned as a predator that mainly ate smaller fish. While little is known of their specific breeding habits, related species in the lake are known to spawn when males turn yellow or orange. During such periods, females may lay up to 400 eggs, which are protected from solar radiation by a dark outer coat.

Travellers today may find it difficult to locate this fish, as it is likely extinct. The population suffered when humans introduced exotic species to the lake between the 1930s and 1950s. Rainbow trout and Argentinian silverside created intense competition and preyed upon the native fish. Survival has been further hampered by the depletion of habitats as people take water from the basins. Modern threats to the lake's remaining wildlife include toxic agricultural runoff, metal pollutants, and the impacts of intensive trout farms.