Loaches are represented by the family, Cobitidae (Loaches and Thorneyes). This family belongs to the order Cypriniformes
(Carp-like fishes). Cobitidae are made up of two sub-families, Botiinae and Cobitinae.
The Cobitidae Family is widespread throughout the Old World. There are several species native to Europe, and a few in Africa (Morocco and Ethiopia), although most species of interest to aquariasts inhabit Asia.
Loaches are generally small to medium sized bottom dwellers rarely exceeding 12" (30 cm) in length. The body shape ranges from the worm-like form of Pangio to the flat-bellied profile of Botia.
Loaches are able to survive in oxygen deficient waters by taking atmospheric air from the water surface and passing it along their intestines to absorb the oxygen. The excess air is passed out the anus.
Loaches possess a spine or spines beneath the eye which can be erected when the fish is threatened by predators. Barbels, containing taste buds, are used to search the substrate for food. Loaches have very small scales giving the body a "skin-like" appearance. Loaches are generally nocturnal (night-active) or crepuscular (active at dusk).
Some Loaches have a habit of resting on their side for long periods of time.
There has been little success in breeding Loaches in captivity. Possibly the recreation of rainy season conditions could inducer spawning.