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Brief Summary

    Clarias gariepinus: Brief Summary
    provided by wikipedia

    Clarias gariepinus or African sharptooth catfish is a species of catfish of the family Clariidae, the airbreathing catfishes.

    Brief Summary
    provided by FAO species catalogs
    Freshwater, widely tolerant of extreme environmental conditions.The presence of an accessory breathing organ enables this species to breathe air when very active or under very dry conditions.Bottom feeder which occasionally feeds at the surface. Omnivorous, a general scavenger. Feeds on insects, crabs, plankton, snails and fish but also take young birds, rotting flesh, plants and fruits.During intra-specific aggressive interactions, this species was noted to generate electric organ discharges that were monophasic, head-positive and lasting from 5-260 ms. Spawning (between July to December) takes place during the rainy season in flooded deltas.

Comprehensive Description

    Clarias gariepinus
    provided by wikipedia

    Clarias gariepinus or African sharptooth catfish is a species of catfish of the family Clariidae, the airbreathing catfishes.

    Distribution

    They are found throughout Africa and the Middle East, and live in freshwater lakes, rivers, and swamps, as well as human-made habitats, such as oxidation ponds or even urban sewage systems.

    The African sharptooth catfish was introduced all over the world in the early 1980s for aquaculture purposes, so is found in countries far outside its natural habitat, such as Brazil, Vietnam, Indonesia, and India.

    Description

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    Jumping upstream in a branch of the Sabie River, Kruger N.P.
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    Specimen in Indonesia
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    Young African catfish caught in the sewers of Rishon LeZion, Israel

    The African sharptooth catfish is a large, eel-like fish, usually of dark gray or black coloration on the back, fading to a white belly. In Africa, this catfish has been reported as being second in size only to the vundu of the Zambesian waters,[1] although FishBase suggests the African sharptooth catfish surpasses that species in both maximum length and weight.[2][3]

    C. gariepinus has an average adult length of 1–1.5 m (3 ft 3 in–4 ft 11 in).[citation needed] It reaches a maximum length of 1.7 m (5 ft 7 in) TL and can weigh up to 60 kg (130 lb).[2] These fish have slender bodies, flat bony heads, notably flatter than in the genus Silurus, and broad, terminal mouths with four pairs of barbels. They also have large accessory breathing organs composed of modified gill arches. Also, only the pectoral fins have spines.[1]

    Habits

    It is a nocturnal fish like many catfish. It feeds on living, as well as dead, animal matter. Because of its wide mouth, it is able to swallow relatively large prey whole. It has been known to take large waterbirds such as the common moorhen.[4] It is also able to crawl on dry ground to escape drying pools. Further, it is able to survive in shallow mud for long periods of time, between rainy seasons.

    African catfish sometimes produce loud croaking sounds, not unlike the voice of the crow.

    Natural spawning

    Spawning mostly takes place at night in the shallow, inundated areas of the rivers lakes and streams. Courtship is preceded by highly aggressive encounters between males. Courtship and mating takes place in shallow waters between isolated pairs of males and females. The male lies in a U-shape curved around the head of the female, held for several seconds. A batch of milt and eggs is released followed by a vigorous swish of the female's tail to distribute the eggs over a wide area. The pair usually rests after mating (from seconds up to several minutes) and then resume mating.

    Parental care for ensuring the survival of the catfish offspring is absent except by the careful choice of a suitable site. Development of eggs and larvae is rapid, and the larvae are capable of swimming within 48–72 hours after fertilization.

    Rearing

    The rearing of the African sharptooth catfish in Africa started in the early 1970s in Central and Western Africa, as it was realized to be a very suitable species for aquaculture, as:

    • It grows fast and feeds on a large variety of agriculture byproducts
    • It is hardy and tolerates adverse water quality conditions
    • It can be raised in high densities, resulting in high net yields (6–16 t/ha/year).
    • In most countries, it fetches a higher price than tilapia, as it can be sold live at the market
    • It matures and relatively easily reproduces in captivity
    • It tolerates difficult conditions in aquaculture

    Hybridisation

    Clarias gariepinus could be easily crossed with Heterobranchus longifillis to get the so-called hybrid Hetero-clarias.[5] This cross has advantages over the Clarias gariepinus:

    • fish cannot reproduce itself (so it won't spend energy on reproduction)
    • fish has white meat (could be preferred by customer)

    Disadvantage of the Hetero-clarias hybrid:

    • susceptible to stress

    Parasites and diseases

    Clarias gariepinus may host several species of digeneans, in addition to other endo- and ectoparasites.[6]

    References

    1. ^ a b Ecotravel South Africa Archived 2011-01-25 at the Wayback Machine.
    2. ^ a b Froese, Rainer and Pauly, Daniel, eds. (2014). "Clarias gariepinus" in FishBase. March 2014 version.
    3. ^ Froese, Rainer and Pauly, Daniel, eds. (2014). "Heterobranchus longifilis" in FishBase. March 2014 version.
    4. ^ Anoop KR, Sundar KSG, Khan BA & Lal S (2009) Common Moorhen Gallinula chloropus in the diet of the African catfish Clarias gariepinus in Keoladeo Ghana National Park, India. Indian Birds 5(2):22-23
    5. ^ B.J. Roosendaal, Fleuren & Nooijen
    6. ^ Jansen van Rensburg, C., van As, J.G. & King, P.H. 2013. New records of digenean parasites of Clarias gariepinus (Pisces: Clariidae) from the Okavango Delta, Botswana, with description of Thaparotrema botswanensis sp. n. (Plathelminthes: Trematoda). African Invertebrates 54 (2): 431–446.[1]

Distribution

    Distribution
    provided by Animal Diversity Web

    North African catfish have been widely introduced around the world. They are found as far south as South Africa and north into northern Africa. They have also been introduced in Europe, the Middle East, and in parts of Asia. They are potamodromous, which means they migrate within streams and rivers (Teugels 1986).

    Biogeographic Regions: palearctic (Introduced ); oriental (Introduced ); ethiopian (Native )

    Distribution
    provided by FAO species catalogs
    Native of Africa, Niger and Nile Rivers. Also extending to southern Africa, in the Limpopo, Orange-Vaal, Okavango and Cunene River systems; and to the Levant with Israel, Jordan, Lebanon and Syria. Widely introduced to other parts of Africa, Europe and Asia. Trade restricted in Germany. Several countries report adverse ecological impact after.

Morphology

    Morphology
    provided by Animal Diversity Web

    North African catfish are elongate with fairly long dorsal and anal fins. The dorsal fin has 61-80 soft rays and the anal fin has 45-65 soft rays. They have strong pectoral fins with spines that are serrated on the outer side (Teugels 1986).

    This species can attain sizes of up to 1.7 meters including the tail and can weigh up to 59 kg when fully grown. They posses nasal and maxiallary barbels and somewhat smallish eyes. Their coloring is dark grey or black dorsally and cream colored ventrally. Adults posses a dark longitudinal lines on either side of the head; however, this is absent in young fish. Adult's heads are coursely granulated, while the head is smooth in the young. The head is large, depressed, and heavily boned. The mouth is quite large and subterminal (Skelton 1993).

    Other Physical Features: ectothermic ; bilateral symmetry

    Sexual Dimorphism: male larger

Size

Diagnostic Description

    Diagnostic Description
    provided by FAO species catalogs
    Body elongate. Head large, depressed and bony with small eyes. Narrow and angular occipital process;

    gill openings wide; air-breathing labyrinthic organ arising from gill arches; first gill arch with 24 to 110 gillrakers;

    cleithrum pointed, narrow with longitudinal ridges and with sharpness. Mouth terminal, large. Four pairs of barbels present.

    Long dorsal and anal fins; without dorsal fin spine and adipose fin. Anterior edge of pectoral spine serrated. Caudal fin rounded.

    Colour varies from sandy-yellow through gray to olive with dark greenish-brown markings, belly white.

    Can be confused with: The morphology of the cleithrum appears as a useful character to distinguish the closely related catfish species, Clarias anguillaris and C. gariepinus . Elsewhere, the difference seems less distinct, although the presence of a pointed cleithrum is typical for C. gariepinus (Benech et al ., 1993).

Habitat

    Kwando River Habitat
    provided by EOL authors
    The Kwando River system is generally construed to consist of the upper Kwando originating in the Angolan headwaters, the middle reach Linyanti swamps and the lower reach Chobe River. The 170 centimeter (cm) in length north African catfish (Clarias gariepinus) is the largest benthopelagic species native to the Kwando River system. Ion concentrations jgenerally in the rapid flowing river mainstem tends to be low in ionic content; however, swampy areas often contain higher concentrations of nitrate and other ionic components. Correspondingly, planktonic content is only appreciable at these slackwater portions of the river, notably in the Linyanti Swamp. The Kwando waters generally exhibit a lower pH level than the neighboring Okavango River, but have a slightly higher sulfate concentration. The 61 cm three spotted tilapia (Oreochromis andersonii) is another notably large benthopelagic species occurring in the Kwando waters. The 15 cm long benthopelagic thicklipped happy (Thoracochromis albolabris) is the only endemic fish recorded in the Kwando river basin.
    Habitat
    provided by Animal Diversity Web

    North African catfish live in a variety of freshwater environments, including quiet waters like lakes, ponds, and pools. They are also very prominent in flowing rivers, rapids, and around dams. They are very adaptive to extreme environmental conditions and can live in pH range of 6.5-8.0. They are able to live in very turbid waters and can tolerate temperatures of 8-35 degrees Celsius. Their optimal temperature for growth is 28-30 degrees Celsius (Teugels 1986).

    They are bottom dwellers and do most of their feeding there. They are also obligate air breathers, which means they do spend some time on the surface. This species can live in very poorly oxygenated waters and is one of the last species to live in such a uninhabitable place (Pienaar 1968). They are also able to secrete mucus to prevent drying and is able to burrow in the muddy substrate of a drying body of water (Skelton 1993).

    Range depth: 4 to 80 m.

    Habitat Regions: tropical ; freshwater

    Aquatic Biomes: pelagic ; benthic ; lakes and ponds; rivers and streams; temporary pools; brackish water

Trophic Strategy

    Trophic Strategy
    provided by Animal Diversity Web

    North African catfish are omnivores. They are not specific in their food requirements. They are known to feed on insects, plankton, snails, crabs, shrimp, and other invertebrates. They are also capable of eating dead animals, birds, reptiles, amphibians, small mammals, other fishes, eggs, and plant matter such as fruit and seeds. Because they are mobile on land, they are able to prey on terrestrial organisms. This species may also hunt in packs on occasion by herding and trapping smaller fish. They are also refered to as sharptooth catfish because of fine, pointed bands of teeth (Skelton 1993).

    Animal Foods: birds; mammals; amphibians; reptiles; fish; eggs; carrion ; insects; terrestrial non-insect arthropods; mollusks; aquatic crustaceans; other marine invertebrates; zooplankton

    Plant Foods: seeds, grains, and nuts; fruit

    Primary Diet: omnivore

Associations

    Associations
    provided by Animal Diversity Web

    North African catfish are an important player in certain ecosystems. In Thailand, they have been introduced as a farm fish. However, in these marshes and swamps where they are raised, there is a native catfish, walking catfish, that is nearing extinction. This is due to the population expansion of the the North African catfish. It is also due to the back-crossing of the walking catfish and the hybrid of the two species. This is also reducing the genetic variation of the native walking catfish (Na-Nakorn et al 2004). This species is also important in nutrient recycling in conjuction with rice fields. The transfer of nutirents takes place from the pond to the rice via fish feces, which increases rice yields (d'Oultremont and Gutierrez, 2002).

    Associations
    provided by Animal Diversity Web

    Because of the abundance of this species and its lack of mobility on land and in water, it is preyed upon widely. Man is the primary predator, but others include leopards, crocodiles, and birds. The fish eagle and marabou stork are very common predators (Skelton 1993)

    Known Predators:

    • leopards (Panthera pardus)
    • humans (Homo sapiens)
    • crocodiles (Crocodylus)
    • birds (Aves)
    • fish eagles (Haliaeetus)
    • marabou storks (Leptoptilos crumeniferus)

Behavior

    Behavior
    provided by Animal Diversity Web

    It is not known whether this species in particular uses its pectoral spine to make sounds, but in other species of catfish this is very common behavior. This species has also been know to generate electic organ discharges, but it is not known if this behavior is communicative (Teugels 1986).

    Communication Channels: acoustic ; electric

    Perception Channels: visual ; tactile ; acoustic ; chemical

Life Cycle

    Life Cycle
    provided by Animal Diversity Web

    North African catfish lay their eggs in vegetation. The eggs hatch within 25-40 hours. The larvae are able to swim and are able to feed within 2 or 3 days. Growth is very rapid, with males reaching an ultimately larger size than females (Skelton 1993).

    Development - Life Cycle: metamorphosis

Life Expectancy

    Life Expectancy
    provided by Animal Diversity Web

    North African catfish live 8 or more years (Skelton 1993).

    Range lifespan
    Status: wild:
    8 (low) years.

Reproduction

    Reproduction
    provided by Animal Diversity Web

    This species participates in mass spawning.

    Mating System: polygynandrous (promiscuous)

    This species in known to breed in the summers after the rainy season. Vast numbers migrate to "flooded shallow grassy verges of rivers and lakes" (Skelton 1993). The eggs are laid in the vegetation.

    Breeding season: Summer

    Average gestation period: 25-40 hours.

    Key Reproductive Features: seasonal breeding ; sexual ; fertilization (External )

    Further research should be done on the amount of parental care given in this species.

    Parental Investment: no parental involvement

Conservation Status

    Conservation Status
    provided by Animal Diversity Web

    US Federal List: no special status

    CITES: no special status

Benefits

    Benefits
    provided by Animal Diversity Web

    Because north African catfish are heavily farmed around the world, there are some adverse effects on native populations of fishes. North African catfish breed with native walking catfish, which produce some sterility when back crossing occurs (Na-Nakorn et al, 2004). Another adverse effect of fish farming in general is the effect of fish farm waste on the surrounding ecosystem. There are large amounts of feed and fecal matter near fish farms. This waste is further spread by wild fish and deposited an even further distance from the farm. This kind of dispersal has great effects on the environment. It affects the feeding behavior and performance of other aquatic animals, including other fishes, crustaceans, and mussels (Sara et al., 2004).

    Benefits
    provided by Animal Diversity Web

    North African catfish are a very good food source for humans. They are farmed extensively all over Asia. Because of this, this species and other farmed catfish are involved with extensive diet experiments. These experiements are meant to find the best diet for optimal yield. One such study is attempting to find the optimal dietary carbohydrate to lipid ratio in the fish's diet (Ali and Jauncey, 2004). Another similar study is testing the digestibility of oilseed cakes and meals for use in the fish's diet (Fagbenro, 1998). There are many other studies that are testing similar ideas about the African catfish's diet to improve the success of the farms.

    Positive Impacts: food

    Benefits
    provided by FAO species catalogs
    One of the commercially most important freshwater fishes in Africa. Caught with drawnets. The total catch reported for this species to FAO for 1999 was 27 220 t. The countries with the largest catches were Mali (15 091 t) and Nigeria (9 994 t). Has been imported for purposes of aquaculture and gamefish. Marketed live, fresh and frozen; eaten broiled, fried and baked.