Houting, Lake Constance whitefish, true fera, and Lake Genèva whitefish or little fera, heavily fished, were freshwater benthopelagic whitefish once found in lakes and rivers of Europe feeding on zooplankton and now extinct in their original waters from overfishing, eutrophication of lakes, and hybridization with other whitefish. Of this group, the houting was uniquely anadromous, able to live in either freshwater or saltwater, and once found in rivers draining to the North Sea from Belgium, France, Germany, Netherlands, and England.
This freshwater cod from Australia’s Brisbane River, thought to be a species midway between the Mary River cod and the eastern freshwater cod, are extinct from overfishing, habitat destruction, and poisoning of its waters after bushfires in the 1930s.
Burnt-tailed barb, a.k.a., Burnt tail fish, a.k.a., Siamese bala-shark, was a small freshwater fish endemic to the Mae Klong and Chao Phraya River basins in Thailand. It hasn’t been found in thirty years.
The New Zealand grayling a.k.a. upokororo, pokororo, paneroro, and kanaekura at just under nine inches long, was a freshwater or brackish, benthopelagic, amphidromous fish, which means they were bottom dwellers born in fresh or brackish waters, that drift into the ocean as larva but return to freshwater to grow into adults and spawn, once found in lowland rivers and streams of New Zealand until deforestation, and disease, competition, and predation from introduced trout resulted in their demise.
The small Maryland darter ate insects, larva, and small snails and favored swiftly flowing rock riffles with crevasses for shelter, but seems to have darted into oblivion, never found a second time in Swan Creek where it had been discovered, ultimately confined to a single riffle in Deer Creek, and then not seen since 1988.
This small pupfish, adapted to hot water, existed in only the outflows of a pair of hot springs in the Mojave Desert. We lost it about 1970 after we diverted the outflows for bathhouses, and after introducing non-native species.