Coregonus fera

Coregonus fera, commonly called the true fera, is a presumed extinct freshwater fish from Lake Geneva in Switzerland and France.

Description
The fera is a freshwater whitefish that typically grows to between 35 and 40 centimeters in length. It is a member of the common whitefish complex (Coregonus lavaretus sensu lato).

The identity of the fera is disputed. In 1950, Emile Dottrens described Coregonus fera as native to both Lake Geneva and Lake Constance. The coregonines from Lake Constance were named Sandfelchen. In 1997, Maurice Kottelat made a revision and used the name Coregonus fera for the Geneva fera and Coregonus arenicolus for theSandfelchen. The common name fera is still also used for fish that continue to live in Lake Geneva, but it now refers to the introduced Coregonus palaea.

Biology
The true fera lived at the bottom of lakes, where it fed on zooplankton and spawned between February and mid-March.

Extinction
Together with the similarly extinct gravenche (Coregonus hiemalis), the fera was one of the most caught freshwater fishes in Lake Geneva. In 1890, these two fishes constituted 68% of the total captures in the lake. Due to a combination of overexploitation and heavy hybridisation with introduced Coregonus species, it became extremely scarce and was last seen in Lake Geneva in 1920.