Speaking at an event on fish care during winters, Dr Meera D Ansal, College of Fisheries, Guru Angad Dev Veterinary and Animal Sciences University (GADVASU) said fish, being a cold blooded aquatic animal, needs special care during winters. As temperature of the surface water is colder than the bottom layers, the fish prefers to live in the bottom zone. Farmers shall keep the water depth up to 6 feet, so that it gets enough space for hibernating in the warmer bottom zone. In shallow waters, the whole water column becomes cold, which affects the fish and can prove fatal. As day length and light intensity also decreases during winters, oxygen levels decline in ponds due to reduced photosynthetic activity. The situation further aggravates during continuous cloudy days. The farmers are advised to aerate their ponds either by adding fresh water or by using aerators, especially during early hours of the day, said Dr Ansal. Feed intake of fish decreases with decrease in temperature as its digestive system becomes sluggish. Hence, it is essential to reduce the feeding rate by 50-75% depending on the temperature. In case the temperature falls below 50 degrees, it is advised to stop feeding. Excess feed remains unconsumed and accumulates at the pond bottom, which deteriorates the water quality. Farmers are further advised to use low protein diets. It is also necessary to reduce/stop adding organic manures such as cow dung, poultry droppings, and pig dung in the pond as rate of decomposition of organic manures declines due to poor microbial activity during winters. It is also advised to go for periodic raking of bottom soil (with the help of barbed wire) to prevent any suspected accumulation of toxic gases at the pond bottom, said the experts. During winters, various fungal, bacterial and parasitic diseases like fin rot, gill rot, EUS and argulosis may appear in the fish. Treat the pond with CIFAX @ 400 ml/acre just before the onset of winters. Also treat the pond with potassium permanganate @ 1-2 kg/acre or limestone @ 50-100 kg/acre. Salt application @ 100 kg/acre also helps in protecting fish against disease outbreak during winters, added Dr Ansal.