The role of water in fish farming.

Water is the natural habitat of fish thus for successful farming venture,the quality must be monitored and controlled.The growth of any fish depends on the water parameters,feeding protocol,feed composition and genetic potential of the fish specie. The sources of water for the fish farming could be any of the following; wells,dams,boreholes ,sea/lagoon and streams.The system of farming intended will dictate the source of water to be used.The earthen pond usually get water from streams,sea/lagoon and channeled springs while the concrete ponds are filled either from wells,boreholes or dams.The most important factor to consider is the quality of the water source. Water for fish farming must possess the following qualities; 1) The PH must be between 7-9,not acidic or too alkaline. 2)The water must be clean and free from contaminants/pollutants such as oil,chemicals,paints or heavy metals. 3)It must be odorless,free from scumb or foam. 4)It must contain enough dissolved oxygen 4mg/litre. 5)It must have a temperature of between 25-32 degree . 6) The carbon dioxide must not be less than 5mg/litre. 7)Ammonia level 0.05mg/litre. 8)Nitrate not less than 50mg/litre. 9)Nitrite not less than 0.30mg/litre. Water quality should be checked at regular intervals using a water kit and necessary adjustment made,a change in any of the water parameters leads to stress in the fish which could lead to severe loses. Oxygen a major index of water quality needs regular monitoring and balancing.The reduced and increased levels of oxygen has a bad effect on the fish.When oxygen level is depleted in the pond,it leads to suffocation and death of the fish,while supersaturation leads togas bubble disease in fish.The supersaturation usually occurs in algae bloom,where there is rapid photosynthesis resulting in small bubbles accumulating in fish intestines,muscles and gills causing the fish to float. The management practices also hamper on the health of the fish,so these must also be taken into consideration in fish farming.

FINGERLING PRODUCTION.

Fingerling production in cat fish farming is an essential part of the farm operation because it is the seed needed for production.The Clarias gariepinus spp is the common cat fish reared in Nigeria because of its early maturity taste,and the fact that it has an accessory breathing organ hence can survive outside water for some hrs,this explains why its sold live in the open markets. The mature male and female brood stock are chosen and kept in separate tubs,one male can fertilize 10 females.The males are bigger and heavier than the females,weighing over 1kg is the ideal .The males must have well developed genitals that are reddish indicating maturity. The females to be used must be identified as good spawners,with a weight of 450-500g,and must be over 8months with dark golden green eggs. The females are usually injected with hormones,the eggs expressed and mixed with milt of the male catfish.The male catfish is killed to extract the milt while the female is returned to pond after eggs are expressed. There are various hormones used in stimulating ovulation in fish such as ova prim, human chorionic gonadotropin, crushed pituitary gland and a combination of motilium and suprefact. The materials needed for the spawning include; a glass trough or a bath tub with water inlet and outlet pipes, screen with stand, pumps,bowls and net covering to keep tank covered and dark.The method you intend to use will dictate materials you will put in place. METHOD; The female brood fish to be used are injected with hormone,and left for 10 hours in a tank with flowing water,after which the eggs are stripped and placed in a bowl and fertilized with sperm from milt sac.The testis are cut in quarters,placed in a cloth and squeezed ,so that the sperm is caught on the bowl of eggs and the mixture is gently stirred.The fertilized eggs are placed on the screen in the bath tub and hatching occurs in 24-30 hours. The eggs can also be spawned in bowls with air pumps,this continuous movement of the water facilitates rapid hatching of the eggs .The eggs start hatching after 24 hours,you observe the hatchlings swimming in the bowl,allow 12 more hours for other eggs to hatch,after which you discard the unhatched eggs. The hatchlings are transferred to nursery tank,but are not fed until the 3rd day when there is complete absorption of yolksac. The fry's are fed with artemia ,and growth is observed and monitored.The fry's are sorted every week until they are a month old,then select the fingerlings for sale or continue rearing and sell as juveniles.