Temporal range: Late Cretaceous – present
G. Cuvier, 1817
– Extant Families -
Catfishes (order Siluriformes) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores (species that eat dead material on the bottom), and even to a tiny parasitic species commonly called the candiru, Vandellia cirrhosa. There are armour-plated types and there are also naked types, neither having scales. Despite their name, not all catfish have prominent barbel. Members of the Siluriformes order are defined by features of the skull and swimbladder. Catfish are of considerable commercial importance; many of the larger species are farmed or fished for food. Many of the smaller species, particularly the genus Corydoras, are important in the aquarium hobby. Many catfish are nocturnal, but others (many Auchenipteridae) are crepuscular or diurnal (most Loricariidae or Callichthyidae for example).
- Distribution and habitat 1
Physical characteristics 2
- External anatomy of catfish 2.1
- Size 2.2
- Internal anatomy 2.3
- Sound production and interpretation 3.1
- Catfish as food 4
- Aquaculture 5
- Catfish as invasive species 6
- Dangers to humans 7
- Timeline 8.1
- See also 9
- References 10
- External links 11
Distribution and habitat
Extant catfish species live inland or in coastal waters of every continent except Antarctica. Catfish have inhabited all continents at one time or another. Catfish are most diverse in tropical South America, Asia and Africa with one family native to North America and one family in Europe. More than half of all catfish species live in the Americas. They are the only ostariophysans that have entered freshwater habitats in Madagascar, Australia, and New Guinea.
They are found in freshwater environments, though most inhabit shallow, running water. Representatives of at least eight families are hypogean (live underground) with three families that are also troglobitic (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 species from among the Aspredinidae and Bagridae, are found in salt water.
In the United States, catfish species may be known by a variety of slang names, such as "mud cat", "polliwogs", or "chuckleheads". These nicknames are not standardized, so one area may call a bullhead catfish by the nickname "chucklehead", while in another state or region, that nickname refers to the blue catfish.
External anatomy of catfish
Most catfish are bottom feeders. In general, they are negatively buoyant, which means that they will usually sink rather than float due to a reduced gas bladder and a heavy, bony head. Catfish have a variety of body shapes, though most have a cylindrical body with a flattened ventrum to allow for benthic feeding.
A flattened head allows for digging through the substrate as well as perhaps serving as a hydrofoil. Some have a mouth that can expand to a large size and contains no incisiform teeth; catfish generally feed through suction or gulping rather than biting and cutting prey. However, some families, notably Loricariidae and Astroblepidae, have a suckermouth that allows them to fasten themselves to objects in fast-moving water. Catfish also have a maxilla reduced to a support for barbels; this means that they are unable to protrude their mouths as other fish such as carp.
Catfish may have up to four pairs of barbels: nasal, maxillary (on each side of mouth), and two pairs of chin barbels, even though pairs of barbels may be absent depending on the species. Many larger catfish also have chemoreceptors across their entire bodies, 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". Because their barbels and chemoreception are more important in detecting food, the eyes on catfish are generally small. Like other ostariophysans, they are characterized by the presence of a Weberian apparatus. Their well-developed Weberian apparatus and reduced gas bladder allow for improved hearing as well as sound production.
Catfish have no scales; their bodies are often naked. In some species, the mucus-covered skin is used in cutaneous respiration, where the fish breathes through its skin. In some catfish, the skin is covered in bony plates called scutes; 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 vertebral 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.
All catfish, except members of Malapteruridae (electric catfish), possess a strong, hollow, bonified leading spine-like ray on their dorsal and pectoral fins. As a defense, these spines may be locked into place so that they stick outwards, which can inflict severe wounds. In several species catfish can use these fin rays to deliver a stinging protein if the fish is irritated. This venom is produced by glandular cells in the epidermal tissue covering the spines. In members of the family Plotosidae, and of the genus Heteropneustes, this protein is so strong it may hospitalize humans, those unfortunate enough to receive a sting; in Plotosus lineatus, the stings may result in death.
Juvenile catfish, like most 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 catfishes generally resemble and develop smoothly into their adult form without distinct juvenile specializations. Exceptions to this are the ariid catfishes, where the young retain yolk sacs late into juvenile stages, and many pimelodids, which may have elongated barbels and fin filaments or coloration patterns.
- All catfish species inventory
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- Langecker, Thomas G.; Longley, Glenn (1993). "Morphological Adaptations of the Texas Blind Catfishes Trogloglanis pattersoni and Satan eurystomus (Siluriformes: Ictaluridae) to Their Underground Environment".
- Hendrickson, Dean A.; Krejca, Jean K.; Martinez, Juan Manuel Rodríguez (2001). "Mexican blindcats genus Prietella (Siluriformes: Ictaluridae): an overview of recent explorations". Environmental Biology of Fishes 62: 315–337.
- Froese, Rainer and Pauly, Daniel, eds. (2007). "Phreatobius cisternarum in FishBase. Apr 2007 version.
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- Texas Dept. Wildlife
- 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, ISBN 978-971-02-0003-0.
- Friel, J P and Lundberg, J G (1996). "Micromyzon akamai, gen. et sp. nov., a small and eyeless banjo catfish (Siluriformes: Aspredinidae) from the river channels of the lower Amazon basin".
- "Channel Catfish". Fairfax County Public Schools. Archived from the original on 2006-06-03. Retrieved 2 December 2006.
- Lundberg, John G.; Berra, Tim M.; Friel, John P. (2004). "First description of small juveniles of the primitive catfish Diplomystes (Siluriformes: Diplomystidae)". Ichthyol. Explor. Freshwaters (PDF) 15 (1): 71–82.
- Friel, John P.; Vigliotta, Thomas R. (2006). , a new species from the Ogôoué River system, Gabon with comments on spiny ornamentation and sexual dimorphism in mochokid catfishes (Siluriformes: Mochokidae)"Synodontis acanthoperca" (PDF).
- Mazzoldi, C.; Lorenzi, V.; Rasotto, M. B. (2007). "Variation of male reproductive apparatus in relation to fertilization modalities in the catfish families Auchenipteridae and Callichthyidae (Teleostei: Siluriformes)". Journal of Fish Biology 70: 243–256.
- "Schoolgirl nets 9ft monster fish".
- "Grizzly Bear-Size Catfish Caught in Thailand". National Geographic News. Retrieved 14 July 2006.
- "Term : humeral process".
- Douglas, Ron H.; Collin, Shaun P.; Corrigan, Julie (15 November 2002). "The eyes of suckermouth armoured catfish (Loricariidae, subfamily Hypostomus): pupil response, lenticular longitudinal spherical aberration and retinal topography" (PDF). Journal of Experimental Biology (The Journal of Experimental Biology) 205 (22): 3425–3433.
- Barros, Marcelo D. M.; Guimarães-Cruz, Rodrigo J.; Veloso-Júnior, Vanderlei C.; Santos, José E. dos (2007). "Reproductive apparatus and gametogenesis of Lophiosilurus alexandri Steindachner (Pisces, Teleostei, Siluriformes)". Revista Brasileira de Zoologia 24 (1): 213–221.
- Brito, M.F.G.; Bazzoli, N. (2003). "Reproduction of the surubim catfish (Pisces, Pimelodidae) in the São Francisco River, Pirapora Region, Minas Gerais, Brazil". Arquivo Brasileiro de Medicina Veterinária e Zootecnia 55 (5): 624.
- Kasumayan, A. O. (2008). "Sounds and Sound Production in Fishes". Journal of Ichthyology 48 (11): 981–1030.
- Lechner, Walter (2014). Young Squeaker Catfish can already talk and listen to their conspecifics. Witzany, G (ed). Biocommunication of Animals. Dortrecht, Springer, 321-335.
- Vance, Theresa L. (2000). "Variation in Stridulatory Sound Production in the Channel Catfish, Ictalurus Punctatus". Bios 71 (3): 79–84.
- Ladich, Friedrich; Michael L. Fine (2006). "Sound-Generating Mechanisms in Fishes: A Unique Diversity in Vertebrates". Communication in Fishes 1: 3–43.
- Amorim, Maria Clara P. (2006). "Diversity of Sound Production in Fish". Communication in Fish 1: 71–105.
- Ladich, Friedrich; Myrberg, Arthur A, Jr. (2006). "Agonistic Behavior and Acoustic Communication". Communication in Fishes 1: 121–148.
- Jenny Baker (1988), Simply Fish p 36-37. Faver & Faber, London.
- "Vitamin D and Healthy Bones". New York State Department of Health. Retrieved 13 July 2007.
- Fatty Fish Not Equal in Good Fats. Reuters. Source: Journal of the American Dietetic Association, July 2008
- "Union Fish Company – Basa/Swai Details". Archived from the original on 9 November 2007. Retrieved 11 November 2007.
- "United States Code, Title 21,343. Misbranded food".
- Fish Labelling (Amendment) (England) Regulations 2006 "Fish Labelling (Amendment) (England) Regulations 2006".
- Morris, J.E. (October 1993). "Pond Culture of Channel Catfish in the North Central Region" (PDF). North Central Regional Aquaculture Center. Archived from the original on 2007-02-06. Retrieved 28 June 2006.
- Rogers, Paul. "Economy of Scales". Stanford Magazine (
- "'Catfish' bred in Asia move up on U.S. food chain"$, Associated Press via L.A. Times, 28 November 2006
- Cole, Nancy (27 January 2006) Catfish imports not slowing. Northwest Arkansas News
- Nico, Leo G.; Martin, R. Trent (2001). "The South American Suckermouth Armored Catfish, Pterygoplichthys anisitsi (Pisces: Loricaridae), in Texas, with Comments on Foreign Fish Introductions in the American Southwest". The Southwestern Naturalist 46 (1): 98–104.
- Wakida-Kusunokia, Armando T.; Ruiz-Carusb, Ramon; Amador-del-Angelc, Enrique (2007). "Amazon Sailfin Catfish, Pterygoplichthys pardalis (Castelnau, 1855) (Loricariidae), Another Exotic Species Established in Southeastern Mexico". The Southwestern Naturalist 52 (1): 141–144.
- Chavez, Joel M.; de la Paz, Reynaldo M.; Manohar, Surya Krishna; Pagulayan, Roberto C.; Carandang Vi, Jose R. (2006). "New Philippine record of South American sailfin catfishes (Pisces: Loricariidae)" (PDF).
- Bunkley-Williams, Lucy; Williams, Ernest H., Jr.; Lilystrom, Craig G.; Corujo-Flores, Iris; Zerbi, Alfonso J.; Aliaume, Catherine; Churchill, Timothy N. (1994). (Hancock), a New Exotic Established in Puerto Rican Fresh Waters"Liposarcus multiradiatus"The South American Sailfin Armored Catfish, (PDF). Caribbean Journal of Science 30 (1–2): 90–94. Archived from the original on 2009-03-04. Retrieved 22 June 2009.
- Liang, Shih-Hsiung; Wu, Hsiao-Ping; Shieh, Bao-Sen (2005). ) in the Kaoping River of Southern Taiwan"Liposarcus multiradiatus"Size Structure, Reproductive Phenology, and Sex Ratio of an Exotic Armored Catfish ( (PDF). Zoological Studies 44 (2): 252–259. Retrieved 22 June 2009.
- Sullivan, JP; Lundberg JG; Hardman M (2006). "A phylogenetic analysis of the major groups of catfish (Teleostei: Siluriformes) using rag1 and rag2 nuclear gene sequences". Mol Phylogenet Evol. 41 (3): 636–62.
- Ferraris, Carl J., Jr.; Miya, M; Azuma, Y; Nishida, M (2007). "Checklist of catfish, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types" (PDF).
- "Catfish Families". All Catfish Species Inventory. Retrieved 28 April 2007.
- Froese, Rainer, and Daniel Pauly, eds. (2007). "Parakysidae" in FishBase. April 2007 version.
- Ng, Heok Hee; Sparks, John S. (2005). "Revision of the endemic Malagasy catfish family Anchariidae (Teleostei: Siluriformes), with descriptions of a new genus and three new species". Ichthyol. Explor. Freshwaters 16 (4): 303–323.
- Ferraris, Carl J., Jr.;
- Rodiles-Hernández, Rocío; Hendrickson, Dean A.; Lundberg, John G.; Humphries, Julian M. (2005). (Teleostei: Siluriformes) a new and phylogenetically puzzling freshwater fish from Mesoamerica"Lacantunia enigmatica" (PDF).
- Lundberg, John G.; Sullivan, John P.; Rodiles-Hernández, Rocío; Hendrickson, Dean A. (2007). , requires an ancient intercontinental passage"Lacantunia enigmatica"Discovery of African roots for the Mesoamerican Chiapas catfish, (PDF). Proceedings of the Academy of Natural Sciences of Philadelphia 156: 39–53.
Below is a list of family relationships by different authors. Lacantuniidae is included in the Sullivan scheme based on recent evidence that places it sister to Claroteidae.
According to morphological data, Diplomystidae is usually considered to be the most primitive of catfish and the sister group to the remaining catfish, grouped in a clade called Siluroidei. Recent molecular evidence contrasts the prevailing hypothesis, where the suborder Loricarioidei are the sister group to all catfish, including Diplomystidae (Diplomystoidei) and Siluroidei; though they were not able to reject the past hypothesis, the new hypothesis is not unsupported. Siluroidei was found to be monophyletic without Loricarioid families or Diplomystidae with molecular evidence; morphological evidence is unknown that supports Siluroidei without Loricarioidea.
The rate of description of new catfish is at an all-time high. Between 2003 and 2005, over 100 species have been 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 70 years (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 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. Also, 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 also 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. On the other hand, our understanding of catfish should increase in the next few years due to work by the ACSI.
Catfish belong to a superorder called the Ostariophysi, which also includes the Cypriniformes, Characiformes, Gonorynchiformes and Gymnotiformes, a superorder characterized by the Weberian apparatus. Some place Gymnotiformes as a sub-order of Siluriformes, however this is not as widely accepted. Currently, the Siluriformes are said to be the sister group to the Gymnotiformes, though this has been debated due to more recent molecular evidence. As of 2007 there are about 36 extant catfish families, and about 3,093 extant species have been described. This makes the catfish order the second or third most diverse vertebrate order; in fact, 1 out of every 20 vertebrate species is a catfish.
The catfish are a monophyletic group. This is supported by molecular evidence.
The Candiru may have a parasitic behaviour, invading the male urethra, although the evidence of this is somewhat inconclusive.
While the vast majority of catfish are harmless to humans, a few species are known to present some risk. Many catfish species have “stings” (actually non-venomous in most cases) embedded behind their fins; thus precautions must be taken when handling them.
Dangers to humans
Representatives of the genus Ictalurus have been introduced into European waters in the hope of obtaining a sporting and food resource. However, 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 freshwaters 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.
Catfish as invasive species
There is a large and growing ornamental fish trade, with hundreds of species of catfish, such as Corydoras and armored suckermouth catfish (often called plecos), being a popular component of many aquaria. Other catfish commonly found in the aquarium trade are banjo catfish, talking catfish, and long-whiskered catfish.
In Asia, many catfish species are important as food. Several walking 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, has 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."
Catfish raised in inland tanks or channels are considered safe for the environment, since their waste and disease should be contained and not spread to the wild.
Catfish are easy to farm in warm climates, leading to inexpensive and safe food at local grocers. About 60% of U.S. farm-raised catfish are grown within a 65-mile (100-km) radius of Belzoni, Mississippi. Channel catfish (Ictalurus punctatus) supports a $450 million/yr aquaculture industry.
Vietnamese catfish (Pangasius) cannot be legally marketed as catfish in the United States, and is subsequently referred to as swai or basa Only fish of the family Ictaluridae may be marketed as catfish in the United States. In the UK, Vietnamese catfish is sold as "Vietnamese river cobbler".
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 Bangladesh and the Indian states of Odisha, West Bengal and Assam catfish (locally known as Magur) is eaten as a favored delicacy during the monsoons. Catfish, locally known as thedu or etta in Malayalam, is popular in the Indian state Kerala.
In Malaysia catfish, called "ikan keli", is fried with spices or grilled and eaten with tamarind and Thai chillies gravy and also is often eaten with steamed rice.
In Indonesia, catfish is usually served grilled in street stalls called warung and eaten with vegetables and soy sauce; the dish is called pecel lele. Catfish can also be eaten with chili sambal as lele penyet (minced catfish). (Lele is the Indonesian word for catfish.)
In Central Europe, catfish were often viewed as a delicacy to be enjoyed on feast days and holidays. Migrants from Europe and Africa to the United States brought along this tradition, and in the Southern United States, catfish is an extremely popular food. The most commonly eaten species in the United States are the channel catfish and the blue catfish, both of which are common in the wild and increasingly widely farmed. Farm-raised catfish became such a staple of the diet of the United States that on 25 June 1987, President Ronald Reagan established National Catfish Day to recognize "the value of farm-raised catfish."
Catfish have widely been caught and farmed for food for hundreds of years in Africa, Asia, Europe, and North America. Judgments as to the quality and flavor vary, with some food critics considering catfish as being excellent food, while others dismiss them as watery and lacking in flavor. 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.
Catfish as food
Sound production in catfish may also be correlated with fighting and alarm calls. 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 catfishes, 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 catfishes produce more stridulatory sounds in disturbance situations and more swimbladder sounds in intraspecific conflicts.
Sound-generating mechanisms are often different between genders. In some catfishes, pectoral fins are longer in males than in females of similar length, 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 catfishes, all males actively produced stridulation sounds before egg fertilization, and the species’ songs were different in pulse number and sound duration.
Catfish also have a sound-generating mechanism in their pectoral fins. Many species in the catfish family possess an enhanced first pectoral fin ray, called the spine, which can be moved by large abductor and adductor 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.
Catfish can produce different types of sounds and also have well-developed auditory reception used to discriminate between sounds with different pitches and velocities. They are also able to determine the distance of the sound's origin and from what direction it originated. This is a very important fish communication mechanism, especially during agonistic and distress behaviors. Catfish are able to produce a variety of sounds for communication that can be classified into two groups: drumming sounds and stridulation sounds. The variability in catfish sound signals differs due to a few factors: the mechanism by which the sound is produced, the function of the resulting sound, and physiological differences such as size, sex, and age. To create a drumming sound, catfish use an indirect vibration mechanism using a swimbladder. In these fishes, 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.
Sound production and interpretation
Fish ovaries may be of two types: gymnovarian or cystovarian. In the first type, the oocytes are released directly into the coelomic cavity and then eliminated. 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 occurrence of seminal vesicles, 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, multi-chambered, and connected with the sperm duct, and have been reported to play a glandular and a storage function. Seminal vesicle secretion may include steroids and steroid glucuronides, with hormonal and pheromonal functions, but it appears to be primarily constituted of mucoproteins, acid mucopolysaccharides, and phospholipids.
; the release of spermatozoa is allowed by breaking of the cyst walls.Sertoli cells Spermatocysts are formed from cytoplasmic extensions of .spermatozoa Fringes of the caudal region may present tubules, in which the lumen is filled by secretion and  portions between species.cranial and caudal The total number of fringes and their length are different in the  The anatomical organization of the
The retina of catfish are composed of single cones and large rods. Many catfish have a tapetum lucidum which may help enhance photon capture and increase low-light sensitivity. Double cones, though present in most teleosts, are absent from catfish.
In many catfish, the humeral process is a bony process extending backward from the pectoral girdle immediately above the base of the pectoral fin. It lies beneath the skin where its outline may be determined by dissecting the skin or probing with a needle.
Also in Asia, Jeremy Wade caught a 75.5 kilograms (166.4 lb) Goonch following three fatal attacks on humans in the Kali River on the India-Nepal border. Wade was of the opinion that the offending fish must even have been significantly larger to have taken an 18 year old boy as well as a water buffalo.
These records pale in comparison to a giant Mekong catfish caught in northern Thailand on 1 May 2005 and reported to the press almost 2 months later that weighed 293 kilograms (646 lb). This is the largest giant Mekong catfish caught since Thai officials started keeping records in 1981. This species is not well studied since it lives in developing countries and it is quite possible it can grow even larger.
In North America the largest Ictalurus furcatus (Blue catfish) caught in the Missouri River on 20 July 2010, weighed 130 pounds (59 kg). The largest flathead catfish, Pylodictis olivaris, ever caught was in Independence, Kansas, weighing 56 kilograms (123 lb).
The wels catfish, Silurus glanis, is the only native catfish species of Europe, besides the much smaller related Aristotle's catfish found in Greece. Mythology and literature record wels catfish of astounding proportions, yet to be proven scientifically. The average size of the species is about 1.2–1.6 m (3.9–5.2 ft), and fish more than 2 metres (6.6 ft) are very rare. The largest specimens on record measure more than 2.5 metres (8.2 ft) in length and sometimes exceeded 100 kilograms (220 lb). In July 2009, a catfish weighing 88 kilograms (194 lb) was caught in the River Ebro, Spain, by an 11-year old British schoolgirl.
Catfish have one of the greatest ranges in size within a single order of bony fish. Many catfish have a maximum length of under 12 cm. Some of the smallest species of Aspredinidae and Trichomycteridae reach sexual maturity at only 1 centimetre (0.39 in).