Clarias gariepinus

African catfish (Clarias gariepinus )

The African catfish (Clarias gariepinus ) is a common catfish species from the family of predatory catfish ( Clariidae ).

Biology

African predatory catfish, also called branchial sac catfish or Sharptooth Catfish, have eight barbels and are similar in their cylindrical body the tusk.

Occurrence

African predatory catfish are found in quiet warm rivers, ponds and lakes in Africa and the Middle - East to Asia. Due to their high adaptability African predatory catfish can survive in swamps and in some cases even in sewers. The catfish can survive for several days without water, because they can breathe air through their mouth. Because of their great ecological adaptation they can survive the dry season like the lungfish in desiccated mud at the bottom of lakes. Predatory catfish are adapted to a wide variety of habitats and prefer water temperatures from 20 ° C to 30 ° C, tolerate even a lowering of the temperature to 8 ° C. A salt tolerance of 9.5 ppt was detected, in some regions, keeping African predatory catfish in brackish water.

Way of life

Depending on the water temperature the fry hatch already 18 to 24 hours after oviposition. African predatory catfish are mainly nocturnal and are looking mostly near the ground for food in the form of small molluscs ( Mollusca ) and other small animals up to smaller fish, and carrion. As spawning predators they can cause great damage. Their prey locate them visually or by electromagnetic vibrations. To get to their spawning grounds, African catfish can move briefly on land or passing through narrow passages in new still unsettled waters. It was also observed that they hunted at night in water near shore and humid areas for prey. During the breeding season of waterfowl, larger predatory catfish keep below the flooded trees to capture falling nesting birds. In the Okavango Delta, there is a particular season to a natural phenomenon, the so-called catfish run, when hundreds of African predatory catfish migrate into the flooded area and drive by the beating of their bodies on the papyrus reed plant large quantities of forage fish in the main stream.

In ideal living conditions they can be large and weighing 30 kg and 170 cm. 1992 a 36 -pound African catfish was caught by rod and line in South Africa. 2004 killed a worker weighing 20 kg specimen in the sewers of Dhaka in cleaning.

Economic Importance

Small predatory catfish are sometimes kept in aquariums and are considered very hardy and frugal.

You have because of their savory red meat a growing importance as a food fish and can be produced in aquaculture in large quantities. In the Netherlands African predatory catfishes from tank - circuit installations come under the name Catvis or Meerval in the trade. In Mecklenburg- Vorpommern African catfish are bred in tanks that are heated with waste heat from biogas plants. The Dutch company Fleuren & Nooijen with an annual production of 2 million young fish which are sold for breeding and fattening up to Israel, Nigeria, Ukraine and Costa Rica, is the largest European producer of African catfish prey. In 1993 the world production was 90 013 tonnes.

In the EU Regulation No 506/2008 of the Commission on 6 June 2008 they are described as subject to authorization type. However, the attitude in fish farms and aquaculture is not limited.

In Bangladesh, a national program was initiated in 1998 for the keeping of African catfish prey in miniature pool to life, to enable small farmers a sustainable income. With this measure, especially the women should be considered as " poorest of the poor " through micro-credit and, inter alia, Home production are favored by African catfish. In only 1 m² covered with water holes in the ground almost at every location the catfish can be kept and fed with household waste. Thus it was hoped that a "revolution" in aquaculture in a confined space for developing countries, similar to the introduction of caging in chickens.

African predatory catfish as invasive species

In Bangladesh, the introduction of African catfish prey has brought in some regions of the native fish fauna on the border of extinction because enforce the African catfish robbery against domestic competitors for food greatly. The Indian government warns against the consumption of African catfish prey from the wastewater systems because they, inter alia, to can feed on carcasses and slaughterhouse waste and thus transmit dangerous diseases.

2006 have also been reported from Brazil instances where African robber catfish threaten the native fish fauna.

In Hungary, predatory catfish are kept in warm water aquaculture. It is reported that they had migrated from there in some Austrian waters such as the Raab and Lafnitz. However, fisheries biologists do not believe that could form stable populations due to the freezing temperatures.