LUDHIANA: Monsoon management of fish ponds mainly involves water management skills. Hence, farmers need to manage their ponds smartly to avert any unforeseen damage due to heavy rains. The information was shared by Dr. Meera D Ansal, HoD, Deptt. of Aquacuture, College of Fisheries, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana .
She said that first of all, farmers shall assure that pond dykes are strong enough to withstand erosion during rainfall and this can be achieved by planting grass on the dykes. Erosion adds muddiness to water affecting its productivity due to reduced sunlight penetration leading to oxygen depletion. In case water becomes muddy, application of limestone in accordance to water pH is recommended. Secondly, 1 to 1 ½ feet free board over water surface is required to accommodate the rain water, while an automatic overflow pipe may also be provided for maintaining desired water level during rainfall, but it is to be fixed with a mesh cover to prevent fish loss.
Net fencing can also be provided to prevent fish escape with overflow in case of high intensity rainfall. The third important thing is to keep the dykes 3-4 feet raised above ground level, so that water from catchment area does not enter the pond. It may bring lots of organic load and pesticides from the adjoining agricultural fields and pollute the water, which will affect fish survival and growth, besides posing serious food safety concerns.
Dr Meera Infomer that it is vital to insure that pH of water does not fall below 7.0 due to rainfall, which will be detrimental for fish growth. To prevent any such condition, it is advised to sprinkle limestone on the dykes (@ 10 kg/100m2), so that it mixes with the rainwater and neutralises its acidic effects while entering into the pond. As most of the species breed during monsoon, it is recommended that ponds are not filled with canal water during this season. In case it is the only source of water; farmers need to fix a very fine mesh net on the mouth of the inlet pipe, to prevent entry of eggs and larvae of unwanted fish species (weed and predatory) along with the canal water.
Finally, in case cloudy conditions prevail for long hours during day time, it is suggested to maintain oxygen level through an effective aeration method and stop feeding till next sunshine. It is advocated to periodically replenish 20-25% of pond water with freshwater to maintain optimum pH and oxygen levels during this season, where nutrient rich pond water can be efficiently utilised for irrigating paddy fields, with significant saving on fertilizer costs.