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). (Teugels, 1986)
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). (Pienaar, 1968; Skelton, 1993; Teugels, 1986)
- Range depth
- 4 to 80 m
- 13.12 to 262.47 ft
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). (Skelton, 1993; Teugels, 1986; Skelton, 1993; Teugels, 1986)
- Sexual Dimorphism
- male larger
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). (Skelton, 1993)
- Development - Life Cycle
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. (Skelton, 1993)
- Breeding season
- Average time to hatching
- 25-40 hours
Further research should be done on the amount of parental care given in this species.
- Parental Investment
- no parental involvement
North African catfish live 8 or more years (Skelton 1993). (Skelton, 1993)
- Range lifespan
- 8 (low) years
- Range lifespan
North African catfish are relatively poor swimmers that spends most of the time on the bottom of lakes and rivers (Pienaar 1968). They are, however, able to move across land to another water source during damp conditions (Skelton 1993). They simply extend their strong pectoral fins and spines and begin crawling through shallow pathways.
This species has been known, during intra-specific aggressive interactions, to emit an electric organ discharge that was head-positive and lasting 5-260 milliseconds (Teugels 1986). (Pienaar, 1968; Skelton, 1993; Teugels, 1986)
Communication and Perception
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). (Teugels, 1986)
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). (Skelton, 1993)
- Primary Diet
- Animal Foods
- terrestrial non-insect arthropods
- aquatic crustaceans
- other marine invertebrates
- Plant Foods
- seeds, grains, and nuts
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) (Skelton, 1993)
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). (d'Oultremont and Gutierrez, 2002; Na-Nakorn, et al., 2004)
Economic Importance for Humans: Positive
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. (Ali and Jauncey, 2004; Fagbenro, 1998)
- Positive Impacts
Economic Importance for Humans: Negative
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). (Na-Nakorn, et al., 2004; Sara, et al., 2004)
Hal Gunder (author), University of Michigan-Ann Arbor, William Fink (editor, instructor), University of Michigan-Ann Arbor, Matthew Wund (editor), University of Michigan-Ann Arbor.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- brackish water
areas with salty water, usually in coastal marshes and estuaries.
flesh of dead animals.
uses smells or other chemicals to communicate
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
uses electric signals to communicate
- external fertilization
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
specialized for swimming
- native range
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
found in the oriental region of the world. In other words, India and southeast Asia.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- seasonal breeding
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
Ali, M., K. Jauncey. 2004. Optimal dietary carbohydrate to lipid ratio in African catfish Clarias gariepinus (Burchell 1822). Aquaculture International, 12: 169-180.
Fagbenro, O. 1998. Short communication apparent digestibility of various oilseed cakes/meals in African catfish diets. Aquaculture International, 6: 317-322.
Na-Nakorn, U., W. Kamonrat, T. Ngamsiri. 2004. Genetic diversity of walking catfish, Clarias macrocephalus, in Thailand and evidence of genetic introgression from farmed . Aquaculture, 240: 145-163.
Pienaar, U. 1968. The Freshwater Fishes of the Kruger National Park. Republic of South Africa: The National Parks Board of Trustees of the Republic of South Africa.
Sara, G., D. Scilipoti, A. Mazzola, A. Modica. 2004. Effects of fish farming waste to sedimentary and particulate organic matter in a southern Mediterranean area (Gulf of Castellammare, Sicily): a multiple stable isotope study. Aquaculture, 234: 199-213.
Skelton, P. 1993. A Complete Guide to the Freshwater Fishes of Southern Africa. Halfway House: Southern Book Publishers Ltd..
Teugels, G. 1986. A systematic revision of the African species of the genus Clarias (Pisces: Clariidae).. Annales Musee Royal de l'Afrique Centrale, 247: 1-199.
d'Oultremont, T., A. Gutierrez. 2002. A multitrophic model of a rice-fish agroecosystem: II. Linking the flooded rice-fishpond system. Ecological Modelling, 155: 159-176.