Brachyhypopomus is a genus of fish in the familyHypopomidae (bluntnose knifefish) native primarily to tropical and subtropical South America (south to the Río de la Plata Basin), although a single species, B. occidentalis, also occurs in Panama and Costa Rica.[1][2] They are found in a wide range of static or slow-flowing freshwater habitats such as edges of rivers, streams, floodplains and swamps, but they are absent from deep river channels (a habitat of many other knifefish).[2] There are both species in well-oxygenated waters and poorly oxygenated waters; those in the latter have adaptions that allow them to survive this like larger gills or the capability of gulping up mouthfuls of air from the water surface.[2][3]Brachyhypopomus feed during the night on small invertebrates.[2]
They are small to medium sized knifefish, reaching up to 12–46 cm (4.7–18.1 in) in total length depending on the species involved.[1][2] Overall the various species are similar in general shape, but they do differ in morphometrics and meristics. They vary in general color and pattern, but are well-camouflaged and typically brownish. During the night they change color and become very pale, even species that are dark-colored during the day. Brachyhypopomus are very similar to Microsternarchus and Procerusternarchus.[2]
Species
There are currently 28 recognized species in this genus:[1]
