The Pimelodidae, commonly known as the long-whiskered catfishes, are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

es (

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Siluriformes).

Taxonomy

The family Pimelodidae has undergone much revision. Currently, it contains about 30

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

and about 90 recognized and known but unnamed species. Wikipedia lists 109 species in this family. The low-eye catfish (previously family Hypophthalmidae), and thus the genus '' Hypophthalmus'', which contains four species, was reclassified with the pimelodids. This family previously included fish that are now classified under Pseudopimelodidae (previously subfamily Pseudopimelodinae) and Heptapteridae (previously subfamily Rhamdiinae). This family also previously included '' Conorhynchos conirostris'', currently ''

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

''. However, a molecular analysis has shown unequivocal support for

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

of the individual families and the genus ''Conorhynchos'' into a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

called Pimelodoidea, including Pimelodidae + Pseudopimelodidae and Heptapteridae + ''Conorhynchos''. Some genera have relatively recently been synonymized. ''Merodontotus'' and ''Goslinia'' are now both included under '' Brachyplatystoma''. Also, ''Paulicea'' is now a synonym of '' Zungaro''. The six main groups within Pimelodidae are '' Steindachneridion'', the '' Phractocephalus''-'' Leiarius'' group, the '' Pimelodus'' group, the '' Calophysus'' group, '' Zungaro'', and the '' Sorubim'' group. The ''Pimelodus'' group includes ''Pimelodus'', '' Exallodontus'', '' Duopalatinus'', '' Cheirocerus'', '' Iheringichthys'', '' Bergiaria'', '' Bagropsis'', '' Parapimelodus'', '' Platysilurus'', '' Platystomatichthys'', and '' Propimelodus''. The ''Calophysus'' group includes the five genera '' Aguarunichthys'', '' Pimelodina'', ''Calophysus'', '' Luciopimelodus'', and '' Pinirampus''. The relationships within each genus are still being studied. Most genera lack a hypothesis for

Distribution

All species of Pimelodidae are found in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

and the lower Isthmian region. Their range reaches from South America and

Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...

north to southernmost

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Description

Many long-whiskered catfishes grow to be very large, including the piraiba, ''Brachyplatystoma filamentosum'', reaching about in length. They have three pairs of

barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprini ...

s, with maxillary barbels that may reach the length of the fish's body. Like many other catfishes, their bodies lack scales. The adipose fin is well developed. Many species of Pimelodidae have juvenile forms that appear differently from their adult forms in color pattern, as well as body shape. ''Brachyplatystoma'' species have specialized pelagic young with greatly elongated barbels and fin filaments, and strongly ornamented pectoral spines. Other large pimelodids, such as ''Pseudoplatystoma'', ''Sorubim'', and ''Sorubimichthys'', whose young inhabit vegetated, marginal waters, have distinctive cryptic coloration patterns and much enlarged caudal and pectoral fins.

Ecology

They are generally bottom-living fish, though some are pelagic and probably filter-feeders. They do not guard their young.

Relationship to humans

Because of their large size in many species, pimelodids are an important food fish in South America. Many species have been hybridized through the use of

hormones A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physiology and behavior. Hormones a ...

in an effort to get even larger fish. This same size factor also makes them very popular for sport fishing. Pimelodids are a common addition to Amazonian-themed exhibits in zoos and public aquaria. Despite the looming danger of size in many species, pimelodids remain a popular home

aquarium An aquarium (: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquati ...

fish. Controversy exists over whether or not many of the larger species should be sold in the hobby because of their adult size. Also, some disagreement occurs over hybrids appearing in the hobby, as well. Many species are hardy and easy to take care of. However, it should be taken into consideration what other fish to house pimelodids with, as they do not hesitate to eat other fish that are small enough.

References