Is it time to add two more species to the list of recent extinctions? New research indicates that two critically endangered fish species may now be extinct in the wild following the destruction of their only habitats. The species in question were both killifishes, an order of thumb-size fishes that live in small bodies of fresh or brackish water that are incredibly vulnerable to overexploitation. Similar killifishes live in North America, most notably the nearly extinct Devils Hole pupfish of Nevada.

As reported in the March 2014 newsletter of the International Union for Conservation of Nature (IUCN) Species Survival Commission/Wetlands International Freshwater Fish Specialist Group (pdf), the species Aphanius saourensis of Algeria was last seen in 2004, when the once-widespread fish was down to just a single remnant population. At that time the fish's habitat—the Oued Saoura Basin, an intermittent river—had been severely depleted by agriculture and pollution. Even worse, several species of larger North American fishes from the genus Gambusia were introduced to the region in the middle of the 20th century to control mosquitoes. Instead, they ate the smaller, native fish. Researchers recently spent five days in Oued Saoura and its adjacent water bodies but found no signs of the killifish. They now report that the species is quite likely extinct in the wild.

Another killifish, A. farsicus, also appears to have disappeared in the last few years. The fish, also known as the Farsi tooth-carp, lived in the springs, streams and pools around Iran's Lake Maharlu. That lake, too, has been heavily tapped for agriculture, and the surrounding bodies of water have suffered from lack of rainfall. Researchers report that by 2013 only a single spring remained in the area. And although A. farsicus might still exist there, the spring is "intensively used as a fish farm," leaving few opportunities for the killifish to survive unmolested.

Luckily, both species still remain alive in small numbers in captivity. A. saourensis has been captive-bred since the early 2000s. A. farsicus has three captive assurance populations, one in Iran and two in Europe. But with their native habitats destroyed or inhospitable, the chances of their reintroduction back into the wild seem slim to nonexistent.

There are at least 1,200 known species of killifishes, which all come from the order Cyprinodontiformes and live in harsh environments, but they are very poorly studied. Only a handful of these fishes have ever been assessed for their extinction risk. As the IUCN newsletter reports, "many killifishes are restricted to a few or just one spring areas, lakes or lagoons in arid or semiarid climate regions," and these small bodies of water face pressure around the world. If current trends continue, other killifishes may soon join A. saourensis and A. farsicus as endangered or extinct species.

Note: There are no publicly available photos for either of these species, although you can see a photo of Aphanius saourensis here. Graveyard photo by Matthew Maguire via Flickr. Used under Creative Commons license

Previously in Extinction Countdown: