CULTURE OF CATFISHThere are over 1200 different marine and freshwater catfish, of which only a few freshwater species are important to the commercial farmerIn Europe (Hungary and Yugoslavia), culture of European catfish, sheatfish or wels (Silurus glanis) is well developedIn Asia (Thailand, Vietnam, India, Pakistan, Malaysia, Laos, Cambodia), Clarias batrachus (walking catfish), Clarias macrocephalus (Asian catfish) and Pangasiodon hypophthalmus (=Pangasius sutchi) (Stripped catfish) are culturedIn USA, Channel catfish (Ictalurus punctatus) is most widely cultured. Other cultured species are Blue catfish (Ictalurus furcatus) and White catfish (Ictalurus catus)In Africa, African catfish (Clarias gariepinus) is widely cultured species

CULTURE OF CATFISH

Low market value specis- low in food chain (herbivorous, planktivorous, omnivorous) - Carps, tilapia, milk fishHigh market value species- high in food chain (carnivorous)-High income group countries- Yellowtail, seabream/seabass, salmonidsMiddle and low income group countries- catfishes, snakeheads

Silurus glanis (Linnaeus, 1758)

Clarias macrocephalus (Günther, 1864)

Ictalurus punctatus (Rafinesque, 1818)

Ictalurus punctatus

Clarias gariepinus (Burchell, 1822)

Clarias gariepinus

Pangasiodon hypophthalmus (Sauvage, 1878)

Pangasiodon hypophthalmus

AFRICAN CATFISH, Clarias gariepinusThere are 32 valid species of Clarias in Africa. Of these C. gariepinus is most important for aquaculture. It is synonymus with Clarias lazeraHas an almost pan-African distribution, fron Nile to west Africa and from Algeria to Southern AfricaHas been introduced to other countries outside AfricaInhabits calm waters from lakes, streams and rivers to swamps, some of which are subject to seasonal dryingBody elongated cylindrical; dorsal and anal fins are extremely long, nearly reaching the caudal fin; both fins contain only soft fin raysThe outer pectoral ray is a spine. Pelvic fin normally has six soft raysHead is flattened, highly ossifiedHas four pairs of unbranched barbels- one nasal, one maxillar (longest) and two mandibularHas scaleless skin which is darkly pigmented in the dorsal and lateral parts of the body

AFRICAN CATFISH, Clarias gariepinusColour uniform, ranges from greyish olive to blackish according to substrateThe accessory breathing organ allows the fish to survive for mabny hours out of water or few weeks in muddy marshesFeeds mainly on aquatic insects, fish and debris of higher plants. Also feeds on terrestrial insects, molluscs, fruitsMay be considered as omnivorous with a high tendency to predationThere is no prominent sexual dimorphism except the males have a more pointed uro-genital papilla whereas this papilla has the form of a longitudinal grooveIn natural subtropical climate, first maturity reaches after one year of age (200-300 g)Under artificial conditions, C. gariepinus matures after about six months when they have attained weight of about 200 g.

AFRICAN CATFISH, Clarias gariepinus

In nature, fecundity ranges from 10,000 to 2,00,000 eggs/female (250-2000 g). Eggs are slightly oblong and have a yellowish-green colour. Size of egg is 1.2-1.6 mm.One gram of stripped eggs contain 600-900 eggsPeak maturity occurs during July-September in tropical areasSpawning takes place mostly at night in recently inundated marginal areas of a lake, stream or riverNo parental care except careful choice of a suitable siteDevelopment of eggs and larvae is rapid and larvae are able to swim within 48-72 hrs of fertilizationAs spawning does not occur spontaneously in captivity, artificial methods are required to produce large numbers of fry and fingerlings for culture

ON-GROWING OF AFRICAN CATFISH

Normally grown to market size in earthen ponds, either in monoculture or in polyculture, especially with tilapiaSemi-intensive polyculture and intensive monoculture are carried out in ststic ponds, using double crop system in a yearOptimum size of grow-out ponds is 0.04-0.10 haRectangular pondAverage water depth 1.0 m

SEMI-INTENSIVE POLYCULTURE OF AFRICAN CATFISHBased on fertilization and supplementary feedingIn such system, catfish will thrive on zooplankton, benthos, tilapia offspring and supplementary feed whereas tilapia will consume phytoplankton, benthos and supplementary feedPond is prepared in usual wayIn addition, pond should be equipped with atleast one compost crib placed in a corner near the inlet and made of bamboo or wooden stakes. Radius of crib ranges from 1.5 to 3.0 m for 400 to 1000 sq m pond respectivelyA square floating bamboo frame (2-3 m per side) is fixed at the feeding place in pond

STOCKING OF POND OF AFRICAN CATFISH

Fingerlings are stocked as soon as ponds are filled with waterStocking rate depends on the marketable size of fishIf higher marketable size is desired, catfish may be stocked at a lower rate, but not less than 0.5 fingerling/sq mIn polyculture with monosex tilapia (1-2/ sq m), a stocking rate of 0.5-1.0 fingerling catfish/ sq m is recommended, depending on the quality of supplementary feed

Species Marketable size Weight of fingerling

Stocking rate

Catfish 200 g 1-5 g 2 fingerling/cu m

Tilapia 100 g 5-20 g 2 fingerling/cu m

POND FERTILIZATION FOR AFRICAN CATFISH

After stocking, the natural production of pond should be regularly maintained by addingg mainly organic fertilizersPrior to water filling, each compost crib is filled up with layers of organic material such as animal waste, agricultural waste(grass, vegetable waste, brewery waste etc) household waste (spoiled fruits, kitchen waste, ashes) or ready-made compostAfter stocking of fish, compost crib should be maintained by adding organic waste at regular intervals, according to the degree of decomposition of compost and plankton development (water colour, transparency)Alternatively, ponds can be regularly fertilized by keeping organic material ready at pond’s edge

SUPPLEMENTARY FEEDING OF AFRICANCATFISH

Day Estimated Biomass

(kg/100 sq m)

Feeding Rate (%/day)

Amount of Feed (g/100 sq

m/day)Stocking 2.6 8.5 200

30 5.4 5.5 30050 11.5 3.5 40090 21.4 2.5 500120 30.0 2.0 600150 42.8 1.6-2.0 700-900180 52.6 - harvest

INTENSIVE MONOCULTURE OF AFRICAN CATFISH

Preparation of pond is similar to that of polyculture except compost cribStocking: 2-10 fingerling/cu m corresponding to a marketable size of 500 and 200 g respectively after 6 monthsFeeding: feed of 40-45% crude protein level at the rate of 2 to 8% of body weigh daily in two instalements ( morning and evening)Harvesting: after 6 monthsHarvested weight: 200-250 g at stocking rate of 10 fingerling/ sq mSurvival 50-70%