Brachyplatystoma

Brachyplatystoma is derived from the Greek words brachy, platy, and stoma, which mean "short", "flat", and "mouth", respectively. This genus was described in 1862 by Pieter Bleeker. Brachyplatystoma and its monotypic sister species Platynematichthys are the only genera in the tribe Brachyplatystomatini. These two genera are characterized by two synapomorphies; these include a gas bladder divided into an anterior portion and a triangular posterior portion, as well as a ventral crest under the cleithrum, the main bone supporting the pectoral fins. The genus Brachyplatystoma was previously not monophyletic; to correct this, the genera Merodontotus and Goslinia are now both included under Brachyplatystoma. Furthermore, a new species was described in 2005, which brings the species count to seven extant species. B. capapretum is sister to B. filamentosum. • Subgenus Brachyplatystoma: • Brachyplatystoma juruense (Boulenger, 1898) (Zebra catfish, Juruense catfish, Gold Zebra Pim, False Tigrinus) • Brachyplatystoma platynema Boulenger, 1898 (Slobbering catfish) • Brachyplatystoma tigrinum (Britski, 1981) (Tigerstriped catfish, Zebra shovelnose, Royal tiger shovelnose) • Brachyplatystoma vaillantii (type) (Valenciennes, 1840) (Laulao catfish, Piramutaba) • Subgenus Malacobagrus • Brachyplatystoma capapretum (Lundberg & Akama, 2005) (Blacktail Piraíba) • Brachyplatystoma filamentosum (Lichtenstein, 1819) (Kumakuma, Piraíba, Filhote) • Brachyplatystoma rousseauxii (Castelnau, 1855) (Gilded Catfish, Dourada) • †Brachyplatystoma promagdalena Lundberg, 2005 – only known from a fragmentary Weberian complex (part of the vertebral column behind the head), Miocene origin fossil species found in Colombia. B. flavicans is not actually a species of Brachyplatystoma; this name is a commonly used synonym of Zungaro zungaro. Strict consensus phylogenetic tree based on six most parsimonious trees of pimelodids: }} ==Anatomy and appearance==

These catfish are generally streamlined fish, being powerful swimmers. Many Brachyplatystoma spp. exhibit countershading, in which the dorsal surface of the body is darker, paired with a lighter underbelly. In many species, this is consistent throughout life, though there are some exceptions: juvenile B. capapretum and B. filamentosum exhibit dorsal and lateral spots which mostly disappear in the adult form, while juvenile B. juruense and B. tigrinum exhibit lateral spots that expand to form dense vertical stripes as the fish matures; The other species range in size from about , though some are smaller still, around 60 cm (23 inches) in length. The world record recognized by IGFA for Brachyplatystoma filamentosum belongs to the Brazilian, Jorge Masullo de Aguiar with . B. filamentosum and B. rousseauxii have a mysterious "milk" gland at the anterior upper part of their pectoral fins. Its function is unknown, but in Colombia this fish is known as lechero, which means milkman. ==Distribution and habitat==

Fish of this genus are found throughout the Amazon, Orinoco, and The Guyanas in South America. The genus does not occur west or north of the Andes or in the Venezuelan Coastal Range. These fish generally inhabit areas that have a soft substrate, such as mud or sand. The fossil catfish B. promagdalena has been found in Colombia in an area now drained by the Magdalena River, where Brachyplatystoma species are currently absent; during the Miocene, this area had been drained by the Amazon and Orinoco system. The pair of larger species, the piraíba and dark-caped piraíba, have a wider range of habitats than the smaller species; the smaller species are confined to river channels and estuaries, while the pair may enter floodplains. ==Ecology==

These fish are mainly piscivorous preying on smaller fish such as characins, cichlids, and other catfish. The young, sometimes referred to as alevins, are carried downstream, during which they develop through their larval stages, the specific identities of these may be hard to determine, though the use of meristics such as myomere count is possible. Juveniles and subadults are commonly found in brackish habitats, such as estuaries, After reaching a certain size, juveniles swim upriver, beginning their migration towards their spawning grounds. ==Relationship to humans==

Brachyplatystoma are important food fish. In the Amazon Basin, thousands of metric tons of fish from this genus are caught for both local consumption as well as exportation. with B. rousseauxii being considered one of two most important catfish species caught in the Amazon River basin. Based on a review by IBAMA, B. vaillantii was by far the most caught fish by weight in the Brazilian Amazon in 1998, B. rousseauxii the fourth most caught and B. filamentosum the sixth (Semaprochilodus spp. second, Prochilodus nigricans third and Brycon spp. fifth). Fishing for Brachyplatystoma spp. may be done in estuaries, where juveniles feed and grow in preparation for their upstream migration, and where bycatch species such as Plagioscion squamosissimus and Sciades herzbergii reside. Because these fish may migrate back to their original tributary, overfishing in a certain area may diminish overall catches as a whole genetic group is depleted. Catch rates of B. filamentosum have decreased drastically from 1977; Other Brachyplatystoma spp. may also be at a similar risk. Gold prospecting may also frighten these large catfishes in the areas where they spawn. Conversely, there have been incidents where large B. filamentosum have supposedly preyed on humans. Furthermore, in one account documented on the television series River Monsters, a local fisherman was apparently found having been swallowed head-first up to his waist by a piraíba, with neither the fish nor the fisherman surviving the encounter. However, the episode itself states that the details surrounding this account are vague and unreliable. In the aquarium Brachyplatystoma are generally uncommon in the fishkeeping trade. The large size of many of these fish prohibit them from being maintained in anything but the largest of aquaria, or in public aquariums. B. tigrinum is a highly prized fish in the fishkeeping hobby, and is one of the most expensive fish in this family. These fish should be kept in well-oxygenated aquaria with a high current. Due to their large size, the aquarium should also be spacious and any tankmates must be large enough not to be eaten. The aquarium should not be brightly lit, and hiding places should be available. Breeding is unreported in captivity. ==References==