The summers of North India from March to November are favourable for fish farming. Few smart management tips can boost production and farmers’ income significantly, as informed by Guru Angad Dev Veterinary and Animal Sciences University college of fisheries. Dean college of fisheries Meera D Ansal said during peak summers, the farmers shall maintain 5 to 6 feet of water depth to provide comfortable space for the fish below hot surface layer. Ansal recommended to monitor the “Oxygen” levels during this period, which may fall to lethal levels during dawn due to enhanced biological activity in the pond. She advised to aerate the ponds before sunrise, either by adding fresh water or using aerators, to maintain optimal oxygen levels. If fish are seen gasping for air at water surface, provide aeration, and suspend manuring and feeding till the water quality improves. Periodic water exchange will boost the production and growth of fish. The leftover pond water would be nutrient rich, and can be used for irrigating paddy and other agriculture fields, the dean added.
The vet varsity experts said the plankton production in the pond and feeding as per the recommended regime helps in achieving optimised production targets. For sustained plankton production, manure the pond in a phased manner with split doses. Use farm made pellet feeds to reduce feed wastage and achieve better feed conversion efficiency. In case water turns dark green, brown, greenish brown in colour or algal blooms appear on the water surface, suspend manuring and feeding till the condition improves back to normal. Also check, day and night variation in water pH, which may cross 9.5 during peak day hours and fall below 7.0 during night hours. Maintain optimum pH range of 7.5 to 8.5.
Farmers shall refrain from overstocking, feeding or manuring the ponds for achieving higher productivity. It increases the input cost and deteriorates the water quality. Further, ammonia toxicity rises with increase in temperature and pH, leading to stress and disease outbreak or mortality. Under such conditions, keep the ponds well aerated, add common salt and apply gypsum/alum as per expert advice, said the experts.
The golden rule for disease management in fish farming is “Prevention is better than cure,” as disinfection of large pond water volume is expensive. Unlike terrestrial animals, the individual treatment of underwater fish is not possible. The dean advised the farmers to follow the recommended prophylactic measures with application of lime 50-100 kg per acre, if pH< 8.0, potassium permanganate 1-2 kg per acre or “CIFAX” 400 ml per acre to maintain the fish health; take care of recommended biosecurity measures to check entry of harmful pathogen; and in case of any disease, consult an expert for proper diagnosis and treatment.