How to Farm North African Catfish - Part 1

This guide from the FAO Cultured Aquatic Species Information Programme provides information on farming North African catfish.

Identity

Clarias Gariepinus Burchell, 1822 [Clariidae]

FAO Names: En - North African catfish, Fr - Poisson-chat nord-africain, Es - Pez-gato

Biological Features

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.

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Historical Background

African catfish are mentioned within traditional capture-based aquaculture (known as wheddos in Benin and Ghana and barochois in Mauritius) for centuries. Their culture in modern times follows a similar trend to that of tilapias: first domestication trials by the year 1950 and adoption of the North African catfish Clarias gariepinus as the most desirable catfish for aquaculture in the mid 1970s. However, under culture conditions, it is difficult for the fish to spawn spontaneously. Protocols for artificial propagation based on hormonal stimulation were therefore developed from the 1980s. Research on the development of farming technology has been conducted in Europe (Belgium and the Netherlands) as well as in Africa (e.g. Central African Republic, South Africa, Côte d’Ivoire, Nigeria).

For many reasons, including the current availability of this species in almost all its water bodies, a huge expanding population with increasing demand for fish and its superior technical skill and infrastructures compared to other African countries, Nigeria has certainly benefited by far the most from these research studies.

Generally, Clarias gariepinus have mostly been used as ‘police-fish’ to control over-breeding in mixed-sex tilapia culture in earthen ponds. In Uganda, the development of Clarias culture is more related to its use as baits for fishing in Lake Victoria.

More recently, with the development of balanced extruded feed, there has been a huge diversification of culture environment in most African countries where this catfish is reared, including the use of concrete or fibreglass tanks and water recirculation systems.

Main Producer Countries

The map shown below is constructed from FAO reported statistics for this species. Farming activities also occur in other countries including China, Thailand, Egypt, Uganda.

Main producer countries of Clarias gariepinus (FAO Fishery Statistics, 2006)

Habitat and Biology

North African catfish (generally referred to simply as ‘African catfish’ in the rest of this fact sheet) have almost pan-African distribution (but are naturally absent from the Maghreb, Upper and Lower Guinea and Cape provinces). They are equally present in Jordan, Lebanon, Israel and Turkey. Clarias gariepinus has also been introduced into most other countries in Africa, as well as several in Europe, Asia and South America. Similarly to other species, China has adopted it within its rice-fields and is currently among the main producing countries, even though this species does not appear separately in its production statistics.

This species is found in lakes, streams, rivers, swamps and floodplains, many of which are subject to seasonal drying. The most common habitats are floodplain swamps and pools where they can survive during the dry season(s) due to their accessory air breathing organs. Clarias gariepinus undertake lateral migrations from the larger water bodies, in which they feed and mature at about the age of 12 months, to temporarily flooded marginal areas in order to breed. These reproductive migrations typically take place shortly after the onset of the rainy season(s). The final gonadal maturation is associated with rising water levels. Under stable environmental conditions, adult C. gariepinus have mature gonads year-round. Under ideal conditions, a ripe female may lay about 60 000 eggs/kg. Prior to mating, males compete aggressively for females with which they mate in single pairs, the female swishing her tail vigorously to mix the eggs and sperm and distribute the fertilized eggs. The adhesive eggs stick to submerged vegetation and hatch in 20–60 hours, depending on temperature. The yolk sac is absorbed within 3–4 days and the stomach is fully functional within 5–6 days after onset of exogenous feeding. Sexual differentiation begins between 10 and 15 days after hatching. Larvae feed and grow rapidly in the warm (usually >24 °C) nutrient rich floodplains, reaching 3-7 g within 30 days. As flooded marginal areas dry up with the end of the rains, juveniles and adults make their way back to deeper water. In areas with two rainy seasons, there are usually two reproductive peaks during the year, corresponding in intensity to the magnitude of the rains.

Stomach contents of Clarias species typically include insects (adults and larvae), worms, gastropods, crustaceans, small fish, aquatic plants and debris, but terrestrial seeds and berries, and even birds and small mammals, have also been observed. Larvae are almost exclusively dependent on zooplankton for the first week of exogenous feeding. Large C. gariepinus, because of their high number of gillrakers, also target zooplankton as a primary food source. Although generally omnivorous, C. gariepinus relatively better digests high-protein diets than carbohydrates. Most species of Clarias are slow foraging predators, with very small eyes, using their four pairs of barbels to feel their way around in the dark and find food detected by the array of sensitive taste buds covering the barbels and head. Approximately 70 percent of feeding activity takes place at night. Research in South Africa showed that removal of the barbels reduced feeding efficiency in C. gariepinus by 23 percent. In general, Clarias catfishes capture their prey by gulping them with a rapid opening of the mouth and then retaining them either on the gillrakers or fine recurved teeth arranged on dentary, premaxillary, vomerine and pharyngeal bands. C. gariepinus exhibits a variety of feeding strategies including sucking the surface for terrestrial insects and plant fragments washed into the water by heavy rains and pack-hunting of small cichlids. Growth is relatively rapid, approaching maximum size within a couple of years. First year growth is nearly linear resulting in the large initial jump in size.

Production

Production Cycle

Production cycle of Clarias gariepinus