Vet Varsity Experts share Winter Care Tips for Fish Farming

Ludhiana: Fish is a cold-blooded animal and hence, needs special care during the winter season. Dr. Meera D. Ansal, Dean, College of Fisheries, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana said that during winters farmers shall maintain the pond water depth up to 6 feet to provide enough space to the fish for hibernating in the warmer bottom zone and also add tube well water at dusk to keep the surface water warm, especially when water temperature falls below 15 degree Celsius.

As day length and light intensity decreases during winters, oxygen levels decline due to poor photosynthetic activity in the pond. The situation further aggravates during continuous cloudy days. Hence, the farmers are advised to aerate their ponds either by adding fresh water or by using aerators, especially during early hours of the day. Regular monitoring of water pH is also needed during continuous cloudy days in winters, which may fall to detrimental levels due to poor photosynthetic activity and subsequently accumulation of carbon dioxide. If the water pH falls below 7.0, add lime @ 100kg/acre in two installments.
 In case there are trees (especially deciduous trees) around the pond, trim them during winters so that direct sunlight could fall over the pond and leaves do not fall into it, which may deteriorate the water quality. Further, shaded ponds are more susceptible to oxygen depletion during winters.

Feed intake of fish also decreases with decrease in temperature in winters and hence, it is advised to reduce feeding rate gradually by 25-75% and finally stop when water temperature falls below 10 degree Celsius. Excess feed remains unconsumed and accumulates at the pond bottom and deteriorates the water quality. Further, reduce/stop adding organic manures (cow dung, poultry droppings, pig dung etc.) in the pond, which leads to accumulation of organic matter due to reduced microbial activity. Application of inorganic fertilizers (Urea and SSP/DAP) is also not recommended during this season. It may also lead to development of algal blooms due to instant nutrient enrichment, which blocks sunlight penetration into the pond water. Algal bloom can be controlled by application of either lime @ 50-100 kg/acre or potassium permanganate (KMnO4) @ 2-3kg/acre. The farmers are advised to check the pH of water before lime application. In case it is above 8.5, they shall not use lime.

During winters, various fungal, bacterial and parasitic diseases like fin rot, gill rot, ulcers and argulosis may appear in the fish. Treat the pond with CIFAX @ 400 ml/acre, KMnO4 @ 1-2 kg/acre or limestone @ 50-100 kg/acre to prevent fin/gill rot and ulcers. Salt application @ 50-100 kg/acre also helps in protecting fish against parasites and fin/gill rot. Deltamethrin application @ 15 ml/acre, with a booster dose after 15 days, will help in controlling argulus parasites. Protection against predatory birds also needs special care in this season. Reflecting tapes, nets, sound, bird scares etc. can be used for the said purpose. Marketable size fish (>500g) shall be marketed during this season, so as to create enough space for next crop stocking in the month of March/April. / (December 06, 2023)