African Catfish

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

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)

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

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

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

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

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 )

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

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).

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

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).

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

US Federal List: no special status

CITES: no special status

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

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.

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.

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.

To 150 cm; max. weight 60 kg. The record individual from the country of Malawi was 16.1 Kg

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.

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).

Oviparous. Spawning takes place during the rainy season in flooded deltas. The fishes make a lateral migration towards the inundated plains to breed and return to the river or lake soon afterwards while the juveniles remain in the inundated area. Juveniles return to the lake or river when they are between 1.5 and 2.5 cm long (Ref. 34291). First sexual maturity occurs when females are between 40-45 cm and males between 35-40 cm. Eggs are greenish. Incubations lasts little (about 33 hours at 25°C).

Diagnosis: body depth 6-8 times in standard length, head 3-3,5 times in SL (Ref. 34290) or 30-37% SL (Ref. 28714). Head somewhat between rectangular and pointed in dorsal outline; snout broadly rounded; eyes supero-lateral and relatively small (Ref. 248). Teeth on premaxilla and lower jaw small, fine and arranged in several rows; nasal barbels 1/5-1/2 times as long as head in fishes longer than 12 cm, and 1/2-4/5 of head length in smaller individuals; maxillary barbels rarely shorter than head, usually somewhat longer and reaching to a point midway between origin of dorsal fin and insertion of pelvic fins; outer mandibular barbel longer than inner pair (Ref. 34290). Postorbital bones in contact; lower part of head with 2 black, lateral bands (Ref. 81644). Contrary to other Clarias species, Clarias gariepinus has a high number of gill rakers varying from 24-110 (Ref. 248, 34290, 81644, 101841), the number increasing with size of the fish; gill rakers long, slender and closely set (Ref. 248, 34290). Distance between occipital process and base of dorsal fin is short; dorsal fin almost reaches caudal fin; anal fin origin closer to caudal fin base than to snout, nearly reaching caudal fin (Ref. 248). Pelvic fin closer to snout than to caudal fin base (Ref. 248) or about midway (Ref. 28714). Pectoral fin extends from operculum to below 1st dorsal fin rays (Ref. 248). Pectoral spine robust (Ref. 248), serrated only on its outer face (Ref. 248, 81644), the number of serrations increasing with age (Ref. 248). Lateral line appears as a small, white line from posterior end of head to middle of caudal fin base; openings to secondary sensory canals clearly marked (Ref. 248).Description: head large, mean 30.8% SL; frontal fontanel long and narrow; distance between end of dorsal fin and caudal fin short (0.0-7.6% SL, mean 4.3)(Ref. 81644).Colouration: 2 colour patterns can be discerned: uniform and marbled pattern; in uniform pattern, dorsal surface and flanks of body and dorsal parts of pectoral and pelvic fins are generally dark greyish-greenish black, while belly and ventral parts of paired fins are lightly coloured; in marbled pattern, specimens show irregular dark blotches on light coloured background above and laterally, belly and ventral parts of the paired fins are whitish (Ref. 248, 81644). Most specimens show pigmentation bands on both sides of lower surface of head (Ref. 248, 81644), but these might be absent (Ref. 101841). A series of light and dark bands may occur on caudal fin; proximal third of caudal fin lightly coloured while other part is dark; occasionally, irregular black spots may occur on caudal fin (Ref. 248). Never an irregular pattern of small white spots on body (Ref. 101841).

Procamallanus Infection 14. Parasitic infestations (protozoa, worms, etc.)

Dolops Infestation. Parasitic infestations (protozoa, worms, etc.)

Astiotrema Infestation. Parasitic infestations (protozoa, worms, etc.)

Quadriacanthus Infestation. Parasitic infestations (protozoa, worms, etc.)

Frequency of occurence in Caprivi: frequently in sandy streams, abundant in standing deep water, common in shallow swamps (Ref. 37065). Described in most papers as a bottom feeder, which occasionally feeds at the surface (Ref. 248). Omnivorous (Ref. 123180). Feeds mainly on fish as well as on plants and zooplankton (Ref. 248). Shows noctural feedings habits (Ref. 123180).

Dorsal spines (total): 0; Dorsal soft rays (total): 61 - 80; Anal spines: 0; Analsoft rays: 45 - 65; Vertebrae: 56 - 63

Potamodromous. Migrating within streams, migratory in rivers, e.g. Saliminus, Moxostoma, Labeo. Migrations should be cyclical and predictable and cover more than 100 km.

Polyonchobothrium Infestation 2. Parasitic infestations (protozoa, worms, etc.)

Piscicola Infestation (Piscicola sp.). Parasitic infestations (protozoa, worms, etc.)

Trichodinosis. Parasitic infestations (protozoa, worms, etc.)

Fish Louse Infestation 2. Parasitic infestations (protozoa, worms, etc.)

Sanguinicola Disease. Parasitic infestations (protozoa, worms, etc.)

Phyllodistomum Infestation 8. Parasitic infestations (protozoa, worms, etc.)

Gyrodactylus Infestation 5. Parasitic infestations (protozoa, worms, etc.)

Henneguya Infection 4. Parasitic infestations (protozoa, worms, etc.)

Chilodonella Infection. Parasitic infestations (protozoa, worms, etc.)

Neodactylogyrus Infestation 2. Parasitic infestations (protozoa, worms, etc.)

Macrogyrodactylus Infestation 1. Parasitic infestations (protozoa, worms, etc.)

Adults occur mainly in quiet waters, (vegetated fringes of) rivers and lakes, (isolated) pools (Ref. 248, 28714), irrigation and sewage effluent canals (Ref. 28714), and prefer rather shallow and swampy areas with a soft muddy substrate and calmer water (Ref. 78218). They may also occur in fast flowing rivers and in rapids (Ref. 248, 78218). Recorded as having been or being farmed in rice fields (Ref. 119549). The two known colour types appear to correlate with water turbidity and substrate type (Ref. 81644). Widely tolerant of extreme environmental conditions (Ref. 6465). Water parameters appear to play only a very minor role (Ref. 78218). The presence of an accessory breathing organ enables this species to breath air when very active or under very dry conditions. They remain in the muddy substrates of ponds and occasionally gulp air through the mouth (Ref. 6465). Can leave the water at night using its strong pectoral fins and spines in search of land-based food or can move into the breeding areas through very shallow pathways (Ref. 6868). Omnivorous bottom feeders which occasionally feed at the surface (Ref. 248), but essentially a predator feeding on crustaceans, insects and fish (Ref. 28714). Feed at night on a wide variety of prey (Ref. 6868) like insects, plankton, invertebrates and fish but also take in young birds, rotting flesh and plants (Ref. 6465). Migrate to rivers and temporary streams to spawn (Ref. 34291), and a major floodplain migrant, spawning throughout the flood season, in the Sudd (Sudan) (Ref. 28714). Also caught with dragnets. 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 (Ref. 10479). Known as sharptooth catfish in aquaculture, a highly recommended food fish in Africa (Ref. 52863). Marketed fresh and frozen; eaten broiled, fried and baked (Ref. 9987).

fisheries: minor commercial; aquaculture: commercial; gamefish: yes

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