The Aspredinidae are a small South American family of catfishes (

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Siluriformes) also known as the banjo catfishes, with about 43 species.

Distribution

Aspredinids are found throughout the major tropical rivers of South America (e.g., Magdalena,

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

, Amazon, São Francisco, Paraguay- Paraná, and Uruguay). '' Bunocephalus'' is the only genus found in rivers west of the Andes including the

Atrato Atrato is a municipality and town in the Chocó Department near the Pacific Ocean, Colombia. Climate Atrato has an extremely wet tropical rainforest climate A tropical rainforest climate, humid tropical climate or equatorial climate is a trop ...

San Juan San Juan, Spanish for Saint John, may refer to: Places Argentina * San Juan Province, Argentina * San Juan, Argentina, the capital of that province * San Juan, Salta, a village in Iruya, Salta Province * San Juan (Buenos Aires Underground), ...

, and

Patía River The Patía River () is a river in southwestern Colombia. It flows over to drain into the Pacific Ocean north of Tumaco. The Patía River is the longest river on the Colombian Pacific Coast. The last is navigable by boat. Geography The Patí ...

Taxonomy

Of the 13

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

in the family Aspredinidae, a few genera have been described relatively recently, including '' Acanthobunocephalus'' in 1995, '' Micromyzon'' in 1996, and '' Pseudobunocephalus'' in 2008. These genera are categorized into three subfamilies. The Aspredinidae are often recognized as a part of the primarily Asian superfamily

Sisoroidea Sisoroidea is a superfamily of catfishes (order Siluriformes). It contains the four families Amblycipitidae, Akysidae, Sisoridae, and Erethistidae; many sources also include Aspredinidae. With Aspredinidae, this superfamily includes about 4 ...

as the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

to the family Erethistidae. However, other authors find that they are sister to the superfamily Doradoidea, which includes Doradidae, Auchenipteridae, and perhaps Mochokidae.

Description

The common name of the family "banjo catfishes" refers to their overall body shape, with a depressed head and slender caudal peduncle, that in some species gives the appearance of a

banjo The banjo is a stringed instrument with a thin membrane stretched over a frame or cavity to form a resonator. The membrane is typically circular, and usually made of plastic, or occasionally animal skin. Early forms of the instrument were fashi ...

. Banjo catfishes lack an adipose fin. Most species lack the dorsal spine-locking mechanism. Though their bodies are scaleless, their skin is completely keratinized and is covered by large, unculiferous tubercles arranged in longitudinal rows; the entire outer layer of skin may be shed. Size ranges from less than 2.0 centimetres (.79 in) SL in ''

Hoplomyzon papillatus ''Hoplomyzon papillatus'' is a species of banjo catfish found in Ecuador and Venezuela where it occurs in the Napo and Portuguesa River The Portuguesa River (Spanish: ''Río Portuguesa'', also ''Río la Portuguesa'', ''Río de la Portuguesa'') ...

'' to ''

Aspredo aspredo ''Aspredo aspredo'' is the only species of banjo catfish (order Siluriformes) in the genus ''Aspredo''. This species originates from the lower portions of rivers from Venezuela to northern Brazil. It occurs in the Orinoco delta, through the Gui ...

'' at about 38 centimetres (15 in) SL, though most are less than 15 cm. Most species exhibit cryptic coloration. Aspredinids have a loss of alarm cells and the fright reaction that is present in other ostariophysans. Sexual dimorphism is exhibited in most species in that mature females are typically larger than males; this is, however, reversed in ''

Hoplomyzon sexpapilostoma ''Hoplomyzon sexpapilostoma'' is a species of banjo catfish endemic to Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of S ...

''. Also, in ''Aspredo'' and ''Platystacus'' the dorsal fin spine is much longer in males than in females.

Ecology

Aspredinids live in a variety of habitats ranging from shallow backwaters to deep river channels to tidal estuaries. Some aspredinids appear to be semi

fossorial A fossorial () animal is one adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, meerkats, and mole salamanders, as well as many beetles, wasps, and bees. Prehistoric eviden ...

, during the day often resting slightly buried in leaf litter or other soft substrates. Members of the subfamily Aspredininae inhabit coastal rivers and brackish water habitats such as mangrove swamps.Sands D.: South American Catfishes, Interpet 1988, In general, most species are cryptically pigmented,

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

, and rather sluggish unless disturbed. Like most fish, they are able to swim by undulating their bodies; however, they also propel themselves by pumping water through their gill openings to skip along the substrate. Some species are able to produce sounds by moving their pectoral fin spines back and forth when they are agitated. Most aspredinids are generalized

omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...

s that feed on aquatic and terrestrial invertebrates and organic debris; however, members of ''Amaralia'' appear to specialize in feeding on the eggs of other catfishes. A peculiarity of the catfishes in the subfamily Aspredininae is that after the female's eggs are fertilised by the male, she attaches them to her belly and carries them to shallow water to hatch. In ''Pterobunocephalus'', the eggs are directly attached to the body, while in the other three genera of the subfamily, the eggs are attached to cotylephores, which are fleshy stalks that develop seasonally on the underside of the body that may function in exchange of materials between the mother and her developing embryos. Because these catfish live in muddy environments, this behaviour has been hypothesised to give the eggs better access to oxygenated water. Accounts of reproduction in ''Bunocephalus'' vary; some sources state that they are egg-scatterers without any parental care, while others note them to build a depression for a nest and guard the eggs.

In the aquarium

A few banjo catfishes are kept as aquarium fish, predominantly the smaller members of the subfamily Aspredininae. Their requirements are similar to those of other tropical South American fish, preferring slightly acidic, not too hard water maintained at 20–25 °C (68–77 °F). Since these species are nocturnal burrowers, they need an aquarium with a soft, sandy substrate into which they hide during the daytime and forage in at night. Sharp sand or coarse gravel will damage their whiskers. Although not schooling fish, they are tolerant of their own kind and also get along with other small aquarium species.Editore, Arnoldo. ''Freshwater and Marine Aquarium Fishes''. New York: Simon and Schuster 1976,

References