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Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name for their prominent barbels, which resemble a cat's , though not all catfish have prominent barbels. All siluriformes lack scales, including both the Armoured catfish and naked species. This order of fish are Autapomorphy by features of the skull and swimbladder. Catfish range in size and behavior from the three largest species alive, the Mekong giant catfish from Southeast Asia, the wels catfish of Eurasia, and the piraíba of South America, to detritivorous and scavenging , down to the tiny ectoparasitic species known as the candiru.
In the Southern United States, catfish may be known by a variety of slang names, such as "mud cat", "polliwogs", or "chuckleheads". Such names are regional and unstandardized. For instance, "chucklehead" in one region may refer to a bullhead catfish but indicate blue catfish elsewhere.
Catfish as a group are of considerable Commodity; many of the larger species are farmed or Fishing for food, such as the Pangasius (a shark catfish) and Clarias (like the walking catfish). Many of the smaller species, such as members of the genus Corydoras, are important in the aquarium hobby.
Catfish do not have scales; their bodies are often naked. In some species, their mucus-covered skin is used in cutaneous respiration, where the fish breathes through its skin. In Armoured catfish, the skin is covered in bony plates called ; some form of body armor appears in various ways within the order. In loricarioids and in the Asian genus Sisor, the armor is primarily made up of one or more rows of free dermal plates. Similar plates are found in large specimens of Lithodoras. These plates may be supported by processes, as in scoloplacids and in Sisor, but the processes never fuse to the plates or form any external armor. By contrast, in the subfamily Doumeinae (family Amphiliidae) and in hoplomyzontines (Aspredinidae), the armor is formed solely by expanded vertebral processes that form plates. Finally, the lateral armor of doradids, Sisor, and hoplomyzontines consists of hypertrophied lateral line ossicles with dorsal and ventral lamina.
Juvenile fish catfish, like other fish, have relatively large heads, eyes, and posterior median fins in comparison to larger, more mature individuals. These juveniles can be readily placed in their families, particularly those with highly derived fin or body shapes; in some cases, identification of the genus is possible. As far as known for most catfish, features that are often characteristic of species, such as mouth and fin positions, fin shapes, and barbel lengths, show little difference between juveniles and adults. For many species, pigmentation pattern is also similar in juveniles and adults. Thus, juvenile catfish generally resemble and develop smoothly into their adult form without distinct juvenile specializations. Exceptions to this are the ariid catfish, where the young retain yolk sacs late into juvenile stages, and many pimelodids, which may have elongated barbels and fin filaments or coloration patterns.
Many larger catfish have across their entire bodies (especially the barbels), which means they "taste" anything they touch, and "smell" any chemicals in the water. "In catfish, gustation plays a primary role in the orientation and location of food".Atema, Jelle (1980) "Chemical senses, chemical signals, and feeding behavior in fishes" pp. 57–101. In: Bardach, JE Fish behavior and its use in the capture and culture of fishes, The WorldFish Center, . Because barbels and chemoreception are more important in detecting food, their eyes are generally small, and many species Atrophy them entirely as they adapted to underground environments, becoming cavefish. Like other , they are characterized by the presence of a Weberian apparatus. Their well-developed Weberian apparatus and reduced gas bladder allow for improved hearing and sound production.
The of catfish are composed of single cone cell and large rod cell. Many catfish have a tapetum lucidum, which may help enhance photon capture and increase low-light sensitivity. Double cones, though present in most , are absent from catfish.
The anatomical organization of the testicle in catfish is variable among the families of catfish, but the majority of them present fringed testis: Ictaluridae, Claridae, Auchenipteridae, Doradidae, Pimelodidae, and Pseudopimelodidae. In the testes of some species of Siluriformes, organs and structures such as a spermatogenic cranial region and a secretory caudal region are observed, in addition to the presence of seminal vesicles in the caudal region. The total number of fringes and their length are different in the caudal and cranial portions between species. Fringes of the caudal region may present tubules, in which the lumen is filled by secretion and Spermatozoon. Spermatocysts are formed from cytoplasmic extensions of ; the release of spermatozoa is allowed by breaking of the cyst walls.
The occurrence of , in spite of their interspecific variability in size, gross morphology, and function, has not been related to the mode of fertilization. They are typically paired, multichambered, and connected with the sperm duct, and have been reported to play glandular and storage functions. Seminal vesicle secretion may include and steroid , with Hormone and Pheromone functions, but it appears to be primarily constituted of , acid mucopolysaccharides, and .
Fish Ovary may be of two types - gymnovarian or cystovarian. In the first type, the are released directly into the cavity and then eliminated (released outside the body). In the second type, the oocytes are conveyed to the exterior through the oviduct. Many catfish are cystovarian in type, including Pseudoplatystoma corruscans, P. fasciatum, Lophiosilurus alexandri, and Loricaria lentiginosa.
The wels catfish, Silurus glanis, and the much smaller related Aristotle's catfish, are the only catfish indigenous to Europe; the former ranges throughout Europe, and the latter is restricted to Greece. Mythology and literature record wels catfish of astounding proportions that have not been scientifically verified. The typical size of the species is about , and fish more than are rare. However, they are known to exceed in length and in weight. In July 2009, a catfish weighing was caught in the River Ebro, Spain, by an 11-year-old British schoolgirl.
In North America, the largest Ictalurus furcatus (blue catfish) caught in the Missouri River on 20 July 2010, weighed . The largest flathead catfish, Pylodictis olivaris, ever caught was in Independence, Kansas, weighing . The biggest flathead catfish caught was by Ken Paulie in the Elk City Reservoir in Kansas, US on 19 May 1998 weighing , which was certified by the International Game Fish Association IGFA.
A Mekong giant catfish caught in northern Thailand on 1 May 2005, and reported to the press almost 2 months later weighed . This is the largest giant Mekong catfish caught since Thai officials started keeping records in 1981. Also in Asia, Jeremy Wade caught a goonch following three fatal attacks on humans in the Sharda River on the India-Nepal border. Wade was of the opinion that the offending fish must have been significantly larger than this to have taken an 18-year-old boy, as well as a water buffalo.
Piraíba (Brachyplatystoma filamentosum), a goliath catfish, can grow exceptionally large and are native to the Amazon Basin. They can occasionally grow to , as evidenced by numerous catches. Deaths from being swallowed by these fish have been reported in the region.
The taxonomy of catfish is quickly changing. In a 2007 and 2008 paper, Horabagrus, Phreatobius, and Conorhynchos were not classified under any current catfish families. There is disagreement on the family status of certain groups; for example, Nelson (2006) lists Auchenoglanididae and Heteropneustidae as separate families, while the All Catfish Species Inventory (ACSI) includes them under other families. FishBase and the Integrated Taxonomic Information System lists Parakysidae as a separate family, while this group is included under Akysidae by both Nelson (2006) and ACSI. Many sources do not list the recently revised family Anchariidae. The family Horabagridae, including Horabagrus, Pseudeutropius, and Platytropius, is not shown by some authors but presented by others as a true group. Thus, the actual number of families differs between authors. The species count is in constant flux due to taxonomic work as well as description of new species. Between 2003 and 2005, over one hundred species were named, a rate three times faster than that of the past century. In June 2005, researchers named the newest family of catfish, Lacantuniidae, only the third new family of fish distinguished in the last seventy years, the others being the coelacanth in 1938 and the megamouth shark in 1983. The new species in Lacantuniidae, Lacantunia enigmatica, was found in the Lacantun river in the Mexican state of Chiapas.
The higher-level phylogeny of Siluriformes has gone through several recent changes, mainly due to molecular phylogenetic studies. While most studies, both morphological and molecular, agree that catfishes are arranged into three main lineages, the relationship among these lineages has been a contentious point in which these studies, performed for example by Rui Diogo, differ. The three main lineages in Siluriformes are the family Diplomystidae, the denticulate catfish suborder Loricarioidea (containing the Neotropical "suckermouth" catfishes), and the suborder Siluroidei, which contains the remaining families of the order. According to morphological data, Diplomystidae is usually considered to be the earliest branching catfish lineage and the sister group to the other two lineages, Loricarioidei and Siluroidei. Molecular evidence usually contrasts with this hypothesis, and shows the suborder Loricarioidei as the earliest branching catfish lineage, and sister to a clade that includes the Diplomystidae and Siluroidei; this phylogeny has been obtained in numerous studies based on genetic data. However, it has been suggested that these molecular results are errors as a result of long branch attraction, incorrectly placing Loricarioidei as the earliest-branching catfish lineage. When a data filtering method was used to reduce lineage rate heterogeneity (the potential source of bias) on their dataset, a final phylogeny was recovered which showed the Diplomystidae are the earliest-branching catfish, followed by Loricarioidei and Siluroidei as sister lineages, providing both morphological and molecular support for Diplomystidae being the earliest branching catfish.
The following classification is based on Eschmeyer's Catalog of Fishes:
They are found in fresh water/brackish water environments, with most inhabiting shallow, running water. Representatives of at least eight families are hypogean (live underground) with three families that are also troglobite (inhabiting caves). One such species is Phreatobius cisternarum, known to live underground in phreatic habitats. Numerous species from the families Ariidae and Plotosidae, and a few from Aspredinidae and Bagridae, are found in salt water.Monks N. (editor): Brackish Water Fishes, TFH 2006, Schäfer F: Brackish Water Fishes, Aqualog 2005,
To create a drumming sound, catfish use an indirect vibration mechanism using the swimbladder as a resonating chamber. In these fishes, special sound-producing muscles (sonic muscles) insert on the ramus Mulleri, also known as the elastic spring. The sonic muscles pull the elastic spring forward and extend the swimbladder. When the muscles relax, the tension in the spring quickly returns the swimbladder to its original position, which produces the sound.
In stridulators, the sound-generating mechanism is found in their pectoral fins; the first pectoral fin ray or spine can be moved by large abductor and Adduction muscles. The base of the catfishes' spines has a sequence of ridges, and the spine normally slides within a groove on the fish's pelvic girdle during routine movement; but, pressing the ridges on the spine against the pelvic girdle groove creates a series of short pulses. The movement is analogous to a finger moving down the teeth of a comb, and consequently a series of sharp taps is produced.
Sound-generating mechanisms are often different between the sexes. In some catfish, pectoral fins are longer in males than in females of similar size, and differences in the characteristic of the sounds produced were also observed. Comparison between families of the same order of catfish demonstrated family and species-specific patterns of vocalization, according to a study by Maria Clara Amorim. During courtship behavior in three species of Corydoras catfish, all males actively produced stridulation sounds before egg fertilization, and the species' songs were different in pulse number and sound duration.
Sound production in catfish may also be correlated with fighting and . According to a study by Kaatz, sounds for disturbance (e.g. alarm) and agonistic behavior were not significantly different, which suggests distress sounds can be used to sample variation in agonistic sound production. However, in a comparison of a few different species of tropical catfish, some fish put under distress conditions produced a higher intensity of stridulatory sounds than drumming sounds. Differences in the proportion of drumming versus stridulation sounds depend on morphological constraints, such as different sizes of drumming muscles and pectoral spines. Due to these constraints, some fish may not even be able to produce a specific sound. In several different species of catfish, aggressive sound production occurs during cover site defense or during threats from other fish. More specifically, in long-whiskered catfish, drumming sounds are used as a threatening signal and stridulations are used as a defense signal. Kaatz investigated 83 species from 14 families of catfish, and determined that catfish produce more stridulatory sounds in disturbance situations and more swimbladder sounds in intraspecific conflicts.
Catfish raised in inland tanks or channels are usually considered safe for the environment, since their waste and disease should be contained and not spread to the wild.
In Asia, many catfish species are important as food. Several airbreathing catfish (Clariidae) and shark catfish (Pangasiidae) species are heavily cultured in Africa and Asia. Exports of one particular shark catfish species from Vietnam, Pangasius bocourti, have met with pressures from the U.S. catfish industry. In 2003, the United States Congress passed a law preventing the imported fish from being labeled as catfish. As a result, the Vietnamese exporters of this fish now label their products sold in the U.S. as "basa fish". Trader Joe's has labeled frozen fillets of Vietnamese Pangasius hypophthalmus as "striper."Cole, Nancy (27 January 2006) Catfish imports not slowing. Northwest Arkansas News
Catfish have widely been caught and farmed for food for thousands of years in Africa, Asia, Europe, and North America. Opinions of their quality and flavor vary, with some food critics considering catfish excellent and others dismissing them as watery and lacking in flavor.Jenny Baker (1988), Simply Fish p 36–37. Faver & Faber, London. Catfish is high in vitamin D. Farm-raised catfish contains low levels of omega-3 fatty acids and a much higher proportion of omega-6 fatty acids. Fatty Fish Not Equal in Good Fats . Reuters. Source: Journal of the American Dietetic Association, July 2008
In Central Europe, catfish were often viewed as a delicacy to be enjoyed on and holidays. Migrants from Europe and Africa to the United States brought along this tradition, and in the Southern United States, catfish is extremely popular.
The most commonly eaten species in the United States are the channel catfish and the blue catfish, both common in the wild and increasingly widely farmed. Farm-raised catfish became such a staple of the U.S. diet that President Ronald Reagan proclaimed National Catfish Day on June 25, 1987, to recognize "the value of farm-raised catfish."
Catfish is prepared in a variety of ways. In Europe, it is often cooked in similar ways to carp, but in the United States it is popularly crumbed with cornmeal and fried.
In Indonesia, catfish is usually served fried or grilled in street stalls called warung and eaten with vegetables, sambal (a spicy relish or sauce), and usually nasi uduk (traditional coconut rice). The dish is called pecel lele or pecak lele. Lele is the Indonesian word for catfish. The same dish can also be called as lele penyet (squashed catfish) if the fish is lightly squashed along with sambal with a stone mortar-and-pestle. The pecel or pecak version presents the fish in a separate plate while the mortar is solely for sambal.
In Malaysia, catfish is called ikan keli and is fried with spices or grilled and eaten with tamarind and Thai chili gravy and is also often eaten with steamed rice.
In Bangladesh and the states of Odisha, West Bengal and Assam, catfish (locally known as magur) is eaten as a favored delicacy during the . In the Indian state of Kerala, the local catfish, known as thedu' or etta in Malayalam, is also popular.
In Hungary, catfish is often cooked in paprika sauce (Harcsapaprikás) typical of Hungarian cuisine. It is traditionally served with pasta smothered with curd cheese (túrós csusza).
In Myanmar (formerly Burma), catfish is usually used in mohinga, a traditional noodle fish soup cooked with lemon grass, ginger, garlic, pepper, banana stem, onions, and other local ingredients.
Vietnamese catfish, of the genus Pangasius, cannot be Catfish Dispute in the United States, and so is referred to as swai or basa. Only fish of the family Ictaluridae may be marketed as catfish in the United States.Public Law 107-171, § 10806, 116 Stat. 526-527, codified in and See Piazza's Seafood World, LLC v. Odom , 448 F. 3d 744 (5th Cir. 2006), citing Kerrilee E. Kobbeman, "Legislative Note, Hook, Line and Sinker: How Congress Swallowed the Domestic Catfish Industry's Narrow Definition of this Ubiquitous Bottomfeeder," 57 ARK. L.REV. 407, 411-18 (2004). In the UK, Vietnamese catfish is sometimes sold as "Vietnamese river cobbler", although more commonly as basa.
In Nigeria, catfish is often cooked in a variety of . It is particularly cooked in a delicacy popularly known as "catfish pepper soup" which is enjoyed throughout the nation.
In Jewish dietary law, known as kashrut, fish must have fins and scales to be kashrut. Since catfish lack scales, they are not kosher.
Mythology
In the mythology of the Japanese Shinto religion natural phenomenon are caused by kami. Earthquakes are caused by a giant catfish called Namazu. There are other kami associated with earthquakes. In Kyoto it's usually an eel, but after the 1855 Edo earthquake "catfish prints" were printed giving more popularity to the catfish kami that has been known since the 16th century Otsu-e. In one catfish print the divine white horse of Amaterasu is depicted knocking down the earthquake-causing catfish.
In aquaria
There is a large and growing ornamental fish trade, with hundreds of species of catfish, such as Corydoras and Loricariidae (often called plecos), being a popular component of many aquarium. Other catfish commonly found in the aquarium trade are Aspredinidae, Doradidae, and Pimelodidae.
As invasive species
Representatives of the genus Ictalurus have been introduced into European waters in the hope of obtaining a sporting and food resource, but the European stock of American catfishes has not achieved the dimensions of these fish in their native waters and have only increased the ecological pressure on native European fauna. Walking catfish have also been introduced in the freshwater areas of Florida, with the voracious catfish becoming a major alien pest there. Flathead catfish, Pylodictis olivaris, is also a North American pest on Atlantic slope drainages. Pterygoplichthys species, released by aquarium fishkeepers, have also established feral populations in many warm waters around the world.
See also
External links
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