Mexican blind cavefish aren’t the only blind fish — there are many different species around the world.
Oliver Lucanus |
There are probably close to 200 blind freshwater fish species worldwide. Amazingly, only one species is regularly available in the aquarium hobby: the blind Mexican cavefish (Astyanax mexicanus). There are several reasons for this. A good number of our blind fish are threatened or endangered, as they occur only in caves and are often limited to just one cave in their distribution. Cave systems around the planet are under threat from pollution and dropping water tables because of agricultural practices.
Many blind fish do not occur in caves (so not troglodytic but still found in cavelike conditions) but in the turbid, fast-moving deep-water environments of the Amazon and Congo rivers. In these extreme habitats, collecting fish is difficult and uncommon, given the limited popularity of blind species and the logistics to keep such fish alive.
One oddball example is the Indian subterranean catfish (Horaglanis krishnai), which is endemic to India and was first described in 1950 from specimens taken from a dugout well. The fish inhabit flooded subterranean tunnels, and several have turned up as hand-dug wells penetrate their tunnels. Not much is known about these fish, and they are listed under the “data insufficient” category on the IUCN Red List (iucnredlist.org). There is little chance that we will see a fish like this available in the aquarium hobby.
Want to read the full story? Pick up the June 2012 issue of Aquarium Fish International today.
Give us your opinion on