Catfish farming is one of striving agribusinesses nowadays. It is a flexible agribusiness business that can be virtually done anywhere provided there is space however small. African Catfish, Clarias gariepinus, is a very resilient and prolific fresh water fish. Other catfish species are Clarias batrachus; Clarias ictalurus; Clarias silurus etc. Many farmers in sub-Saharan Africa have successfully raised large tons of adult catfish for market purpose from fingerlings, but, only few knows how to produce fingerlings.
It is important to know how to produce catfish fingerlings. Producing fingerlings will reduce cost of production and provides assurance of getting better output. Fingerlings can be raised up to juvenile stage before stocking. You can also be a good source of quality and healthy catfish seeds (fingerlings or juvenile) for other catfish farmers from your hatchery.
The quality of output you will get will depend on the quality of breeder catfish, breeding materials and of course the method used.
There are simple, medium and re-circulatory system hatchery. However, before setting up
any hatchery, a careful economic planning should be done. This may not be as complicated as you think. A good way to start is to list the income and expenses you expect. First, consider the income your hatchery operation will generate. Generally this means estimating the amount of fingerlings or juveniles you will produce and the price you will receive for them. Next, make a list of the expendable items you will need to buy to produce your fingerlings or juveniles. This will include feed, labour, fuel, electricity, equipment, repair, etc. These are your variable costs. It is important to make a list of costs for everything associated with machinery. These are your fixed costs. Examples include wells, pumps, feed bins, Plastic tanks, buildings, etc.
Fingerlings production requires artificial breeding of catfish, hence, before embarking on breeding exercise, the following equipment/materials should be readily available; Hatchery Facility; Mature Broodstock (300-800 grams); Weighing scale; a pair pincer; Calibrated jug; Thermometer; Mortar and Pestle; Hack saw; Clean water supply; Plastic bowls; hatchery tanks and Spoon; Distilled water; Salt; Hormones (Ovaprim; Ovatid); Dissecting kit; Syringes and needles; Sharp knife/Knife; Kakaban (Egg net) or Substrate; Artemia.
It is important to sterilize all equipment to be used with salt solution to avoid contamination. Breeding activities starts with selection of healthy and matured broodstock (Male & Female spawner/fish), 8 – 12 month of age is preferred, and this should be gotten from a reputable farm.
A female broodstock/fish has well distended, swollen abdomen from which ripe eggs can be obtained by slightly pressing the abdomen toward the genital papilla. Ripe eggs are uniform in size, while a Male broodstock/fish has a swollen, sometimes reddish coloured genital papilla. Female broodstock is injected with synthetic hormones (ovaprim) with a dose of 0.5 ml/kg of body weight. This injection is administered intra-muscularly at the dorsal muscle in the evening hours. Cover the catfish head with a small wet towel to avoid struggling. Ovulation of eggs will start after the hormonal administration. Pituitary gland extract mixed with saline solution (9g salt in 1 litre water) from catfish or carp can also be used.
Male broodstock do not necessarily need hormonal administration, however research by
Adebayo (2014) revealed that, Ovaprim and Ovatide (0.3 ml/kg) significantly increased volume of milt, motility duration and percentage. The efficacy of these synthetic hormones was evident on the reproductive performance as tested on the female C. gariepinus. The use of these hormones in male fish is a means of boosting reproductive performance and ensuring good and viable fish seeds.
The injected female is returned to water.
The speed of ovulation depends on the water temperature, the higher the temperature, the quicker the catfish ovulate.
Afterwards, the hatching tanks using flow through system is prepared by filling it with fresh water and the egg tray/net (kakaban) is gently placed on the hatching tank. Stripping of the female broodstock should be done after latency period of 7 – 12 hours and this is done by gently pressing the abdomen with a thumb from the pectoral fin towards the genital papilla. Ovulated eggs will flow out easily in a thick jet from the genital vent if the females responded well to the hormonal treatment. The ovulated eggs are more or less transparent, flattened and a gram of egg contains approximately 600 – 1000 eggs. The eggs are allowed to fall freely into a clean and dry bowl.
The male catfish cannot be stripped and consequently the sperm can only be obtained by sacrificing a male. The male is killed and thoroughly dried after which the testis is removed and cut with a scissors. The milt is washed out with saline solution (0.9% sodium chloride) unto the egg mass.
Both sperm and eggs remain in their dormant state until they come in contact with fresh water. Then, the eggs are fertilized by adding about the same volume of clean water. The water and egg mass are mixed by gently shaking of the bowl. Eggs must be stirred continuously until they are placed in the hatching tanks as the eggs become sticky and without stirring will stick together into one clump.
Fertilization will take place in about 60 seconds, then, the sperm would have lost its activity, the fertilized eggs are then ready for incubation in hatching tanks. The fertilized eggs are uniformly spread on kakaban/egg net (mesh size – 1 mm) placed on hatching tank.
Flow through system provided below the hatching tank will help maintain optimum oxygen level, if there is no flow through system, ensure, water is renewed in order to provide oxygen. Substrates (with floating ability, e.g strands of sack bundled together, etc.) can also be used in absence of egg net. The substrates are dipped into water containing the eggs and the eggs will stick onto the substrates. They are then transferred into tanks, happa nets or basins, which ever incubation container is available. The incubation of fertilized eggs is for minimum of 24 hours and maximum of 48 hours. A very high temperature between 27oC & 30oC favours quick hatching.
Hatchlings tend to stay in dark places and should not be exposed to direct sunlight; therefore, it is important to cover the incubator container with black tarpaulin. The hatched fries (hatchlings) can survive on egg yolk for 3 days without feed. The fries should be separated from the hatching tank and put into a clean tank to avoid fungal infection and mortality, afterward, the fries shall be fed with Artemia, three times a day until they develop into fingerlings.
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