“Summer season is good for fish farming,” says expert








Aquaculture





In the northwestern states, March/April through October/November is the best time for fish growth; where smart management practices can dramatically increase production and farmers’ incomes. The summer season is favorable for fish growth, but protection from temperatures above 350°C is important, informed Dr. Meera D. Ansal, Dean of College of Fisheries, Guru Angad Dev Veterinary & Animal Sciences University.












Therefore, farmers must maintain a water depth of 5 to 6 feet during peak summer months to provide sufficient comfort zone for fish below the warm surface layer.

She warned to watch ‘oxygen’ levels during this time, which can drop to deadly levels at dawn due to increased biological activity. Therefore, aerate ponds during the early hours of the day before sunrise, either by adding fresh water or using aerators, to keep oxygen levels above 5 mg/l.

If disease and gasping fish on the surface of the water are observed, aerate, add fresh water, apply disinfectant, and suspend manure and feed to improve water quality. Periodic water exchange will further increase fish growth and production. Add fresh water to the ponds and use the nutrient-rich pond water to irrigate the rice fields during this time. This will improve the water quality in the pond and also reduce the need for fertilizer in the rice fields.

Sustained production of plankton (natural food) in the pond and feeding quality food according to the recommended diet helps to achieve optimized production goals. Keep the pond rich in plankton through the mixed use of organic manures and inorganic fertilizers. Use farm-made pelleted feed to reduce feed waste and achieve better feed conversion efficiency.












If the water turns dark green, brown, or greenish-brown and a green, brown, or red algae mat appears on the surface of the water, suspend smoking and feeding until the condition returns. normal. Also check the day-night variation in water pH, which can exceed 9.5 during peak daytime hours and fall below 7.0 during nighttime hours. Maintain optimum pH range (7.5 to 8.5), with application of lime or alum/gypsum as advised by an expert.

Farmers should refrain from anticipating higher production by increasing inputs, i.e. seed, feed and manure/fertilizer. This not only increases the cost of inputs, but also leads to lower production or crop failure. Water quality is deteriorating due to overcrowding, overfeeding and excessive manuring.

Additionally, ammonia toxicity increases with increasing temperature and pH, leading to stress and subsequently disease outbreaks or mortality. Under such conditions, keep ponds well aerated, add common salt and apply gypsum/alum as advised by an expert.












Adhering to the golden rule of “prevention is better than cure” for disease management, Dr Meera advised farmers to follow recommended prophylactic measures with lime (50-100 kg/acre, if pH











First published: May 27, 2022, 07:08 IST


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