Dr. Meera D. Ansal, College of Fisheries, GADVASU said that during winters, temperature of surface water is colder than the bottom layers. Normally fish prefers to live in the bottom zone. Farmers shall keep the water depth up to 6 feet, so that fish gets enough space for hibernating in the warmer bottom zone.
In shallow waters, the whole water becomes cold, which affects the fish. Regular addition of tube well water at dusk helps in keeping the surface of water warm. During the winter season, day length and light intensity also decreases, oxygen levels declines due to poor photosynthetic activity in the pond.
The farmers are advised to aerate their ponds either by adding fresh water or by using aerators, especially during early hours of the day. Water pH may fall to harmful levels during cloudy days due to poor photosynthetic activity and hence higher carbon dioxide levels in the pond.
If there are trees around the pond then cut them during winters so that direct sunlight could fall over the pond. Make sure leaves do not fall in to the pond, as they will add to the organic load and deteriorate the water quality on decomposition.
Feed intake of fish decreases with decrease in temperature. If the temperature falls below 5 degree C, it is advised to stop feeding. Excess feed remains unconsumed and accumulates at the pond bottom, which deteriorates the water quality.
It is also suggested to feed your fish with high protein diets just before the onset of winters. It is also necessary to reduce/stop adding organic manures in the pond. Because the rate of decomposition of organic manures declines due to poor microbial activity during winter season.
Presence of algal blooms is another serious problem during winters as they blocks the penetration of sunlight in to the water. Hence it is recommended to avoid excessive use of inorganic fertilizers during winters.