Ludhiana: Special care needed for fish farming in winter, says vet varsity expert

Dean, College of Fisheries, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Meera Ansal, said fish is a cold-blooded animal, and its body temperature decreases with decline in environmental temperature during winters; hence, optimal water depth of 6 feet shall be maintained in the pond to provide comfortable hibernating space to the fish in the middle and bottom water zones

Guru Angad Dev Veterinary and Animal Sciences University has advised fish farmers to take special care during the winter season to provide comfortable hibernating space to the fish.

Dean, College of Fisheries, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Meera Ansal, said day length, light intensity and photosynthetic activity decrease during winters, which lowers dissolved oxygen content in the water, particularly during continuous foggy days. Hence, farmers should aerate the ponds either by adding fresh water or by using aerators. (HT Photo)

“Unlike terrestrial livestock, fish is a cold-blooded animal, and its body temperature decreases with decline in environmental temperature during winters. Hence, optimal water depth of 6 feet shall be maintained in the pond to provide comfortable hibernating space to the fish in the middle and bottom water zones, besides adding tube well water at dusk to keep the surface water warm, especially when water temperature falls below 15°C,” informed dean, College of Fisheries, Meera Ansal.

Day length, light intensity and photosynthetic activity decrease during winters, which lowers dissolved oxygen content in the water, particularly during continuous foggy days. Hence, farmers should aerate the ponds either by adding fresh water or by using aerators, specifically during dawn, and monitor the water pH during continuous foggy days, which may fall to detrimental levels due to poor photosynthetic activity and subsequent accumulation of carbon dioxide. If the water pH falls below 7.0, 100kg lime per acre should be added in two instalments.

Nearby trees (especially deciduous trees) should be trimmed so that direct sunlight could fall over the pond but leaves do not fall into it, deteriorating the water quality. As fish activity and feed intake decrease with temperature decline, fish feeding reduces gradually by 25-75 percent and finally stops when water temperature falls below 10°C. Excess feed remains unconsumed, accumulates at the pond bottom and deteriorates the water quality. Further, addition of organic manures in the pond should be reduced/stopped, as it increases organic load due to reduced microbial activity. Application of inorganic fertilisers (Urea/DAP) is also not recommended, as it may boost algal blooms instantly and block sunlight penetration into the water. Algal blooms can be controlled by the application of either 50 to 100kg per acre lime (only if the water pH is less than 8.5) or 2 to 3kg potassium permanganate (KMnO4) per acre.

During winters, various fungal, bacterial and parasitic diseases like fin rot, gill rot, ulcers and argulosis may appear in the fish. 400ml CIFAX per acre, 1 to 2 kg KMnO4 per acre, 50 to 100kg limestone per acre or 500gm turmeric powder per acre should be applied to prevent fin/gill rot and ulcers. Application of 50 to 100kg salt per acre is also effective against parasites and fin/gill rot, while 15ml deltamethrin per acre (with a fortnightly booster dose) controls argulus parasite. Reflecting tapes, nylon thread/net covers and sound or bird scares should be used to keep predatory birds away from the pond. Marketable size carp fish (less than 500g) should be harvested during winters (November to February) to create enough space for stocking of the next crop in March/April. However, complete harvesting of winter sensitive Pangas catfish should be done before November 20 to prevent any unforeseen stock loss due to mortality.