The Cetopsidae are a small

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), commonly called the whale catfishes.

Taxonomy

This family contains five

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 ...

divided into two subfamilies, Cetopsinae and Helogeneinae. Helogeneinae was previously a family-level group, but now it has been reclassified as a subfamily of Cetopsidae. This subfamily contains four species in the genus '' Helogenes''. The subfamily Cetopsinae contains four genera. '' Cetopsidium'' contains six species, '' Cetopsis'' contains 21 species, '' Denticetopsis'' contains seven species, and '' Paracetopsis'' contains three species; this makes a total of 37 cetopsines. The genera have been changed as recently as 2005 with the genera ''Bathycetopsis'', ''Hemicetopsis'', and ''Pseudocetopsis'' set in

synonymy A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with ''Cetopsis'' and the description of the new genus ''Cetopsidium''. ''Cetopsidium'' is the sister group to the rest of Cetopsinae. ''Denticetopsis'' forms the next sister group to the remaining cetopsine genera. The tribes Cetopsidiini, Denticetopsini, and Cetopsini are erected for the cetopsine genera.

Distribution

Cetopsids have a wide distribution 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 ...

. Latitudinally, cetopsines extend from northern

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

to central

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. They inhabit major habitats such as the

Orinoco River The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

, Amazon River, and the

Guyanas The Guianas, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British, Dutch, and French Guiana respectiv ...

. In trans-

Andean The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long and wide (widest between 18°S ...

South America, cetopsines are found along the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

slope from the Jurubidá River of Colombia south to the Tumbes River of northern

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

. Along the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

trans-Andean versant, species of cetopsines occur from the

Sinú River Sinú River (), is a river in northwestern Colombia that flows mostly through the Córdoba Department and into the Caribbean. It is the third most important river in the Caribbean Region, after the Magdalena River and the Cauca River. It is ...

of northwestern Colombia east to the

Lake Maracaibo Lake Maracaibo () is located in northwestern Venezuela, between the states of Zulia, Trujillo, and Mérida. While Maracaibo is commonly referred to as a lake, its current hydrological characteristics may better classify it as estuary and/or ...

basin of northwestern

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

. East of the Andean

Cordillera A cordillera is a chain or network of mountain ranges, such as those in the west coast of the Americas. The term is borrowed from Spanish, where the word comes from , a diminutive of ('rope'). The term is most commonly used in physical geogra ...

s, the Cetopsinae occur in the Aroa and Yaracuy River basins along the Caribbean versant of northern Venezuela, through the Orinoco River system and the coastal rivers of the

Guianas The Guianas, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British Guiana, British, Surinam (Dutch colo ...

, south through the Amazon basin to the southern portions of the

Río de la Plata The Río de la Plata (; ), also called the River Plate or La Plata River in English, is the estuary formed by the confluence of the Uruguay River and the Paraná River at Punta Gorda, Colonia, Punta Gorda. It empties into the Atlantic Ocean and ...

basin. Cetopsines also occur in the Juquiá River basin of the state of

São Paulo São Paulo (; ; Portuguese for 'Paul the Apostle, Saint Paul') is the capital of the São Paulo (state), state of São Paulo, as well as the List of cities in Brazil by population, most populous city in Brazil, the List of largest cities in the ...

and the

São Francisco River The São Francisco River (, ) is a large Rivers of Brazil, river in Brazil. With a length of , it is the longest river that runs entirely in Brazilian territory, and the fourth longest in South America and overall in Brazil (after the Amazon R ...

basin of eastern

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. ''Helogenes'', the single genus of Helogeneinae, occurs through much of the Amazon basin, the southern portions of the Orinoco River basin, the coastal rivers of the Guianas, and at least the lower portions of the

Tocantins River The Tocantins River ( , Parkatêjê dialect, Parkatêjê: ''Pyti'' ɨˈti is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" (''Tukã'' for "toucan" and ''Ti'' for "beak"). It ...

Description

The family Cetopsidae includes species of small- to medium-sized catfishes which share an anal fin with a long base, the lack of nasal

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whisker like sensory organ near the mouth (sometimes called whiskers or tendrils). Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the z ...

, and, usually, a lack of

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

and

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

spines. In Cetopsinae, the

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

is highly reduced and is enclosed in a bony capsule. Cetopsines lack an

adipose fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only b ...

, while it may be present (though small) in Helogeneinae. Many species are characterized by small eyes obscured by a thick, overlying

integument In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, Exoskeleton, shell, germ or Peel (fruit), rind. Etymology The term is derived from ''integumentum'', which is Latin for "a coverin ...

that make them appear blind. The dorsal and pectoral fins usually lack spines, except in ''Cetopsidium'' (both present) and ''Denticetopsis'' (only pectoral spines present). In most species of ''Cetopsis'' and ''Cetopsidium'', mature males have a convex margin to their anal fin and elongated distal filaments of the dorsal and pectoral fin spines. The maximum length of this family is about SL in Cetopsinae. ''Cetopsidium'' species are generally smaller in body size than ''Cetopsis''. The maximum length in ''Helogenes'' species is .

Ecology

Most cetopsids feed on insects. '' C. candiru'' and '' C. coecutiens'' are well known to have extremely voracious appetites; these species will attack

carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...

, other living fish trapped in

gillnet Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

s, and even

people The term "the people" refers to the public or Common people, common mass of people of a polity. As such it is a concept of human rights law, international law as well as constitutional law, particularly used for claims of popular sovereignty. I ...

. Some people erroneously believe these fish are

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

like parasitic catfishes, as they are also referred to as "candiru".

References

{{Authority control Fish of South America Catfish families Taxa named by Pieter Bleeker