Stocking and Post Stocking Management in Nursery Pond

Stocking

• After satisfying the physico-chemical nature of the water and plankton growth in the nursery pond, the spawn can be stocked in the ponds at the rate of 5-6 million spawn/ha. However, higher densities of 10-20 million/ha can be followed in cement cisterns
• The stocking should be done either in the early morning or late evening after gradual acclimatization of the spawn to the pond water.
• In nursery, monoculture of carp species is usually recommended.

Stocking of spawn in nursery pond

Post-stocking pond management

• After preparing the nursery pond, it is better to maintain optimal physico-chemical properties and plankton.
• Brown colour of water reveals rich zooplankton growth. Green or blue colour reveals predominance of algae in the plankton. Dirty colour reveals suspension of silt in the water column.
• Maintenance of one metre water depth is enough in nursery ponds.
• Among the chemical properties, 3-8 ppm dissolved oxygen is good for stocking spawn. Carbon dioxide above 15-20 ppm is lethal to fish life. A pH ranging between 7.5 to 8.5 is highly productive. The total alkalinity of 100-125 ppm is highly productive in water. 0.2 to 0.4 ppm of phosphates is good for plankton production and 0.06 to 0.1 ppm nitrates are considered enough for fish growth.
• 1 ml of plankton in 50 litres of water in nursery ponds is considered to be conducive for stocking spawn.

Feeding

• After stocking, during one or two days most of the plankton will be consumed by the spawn.
• Survival and growth of spawn are influenced by quality and quantity of food available in the pond.
• To ensure healthy growth of spawn, artificial feeding is necessary and is restored from the next day after stocking.
• The major carp spawn of 5-6 mm length weighs 0.0014 mg. The most commonly used artificial feeds are groundnut oil cake, rice bran, coconut, mustard cakes, etc.
• Finely powdered and sieved groundnut oil cake and rice bran mixed at 1:1 are used.
• The feeding schedule is as follows.

1. 1-5 days after stocking - double the initial body weight of the spawn.
2. 6-10 days after stocking - thrice the initial body weight of spawn.
3. 11-15 days after stocking - three to four times the initial body weight of the spawn.

• The level of artificial feeding has to be decided by the fish farmer based on the study of physico-chemical parameters and plankton. 

Harvesting

• In 15 days of nursery rearing, the spawn grows to 20-30 mm size fry. At this stage, these fry could be transferred to rearing ponds.
• Supplementary feeding should be stopped a day before harvesting.
• The harvesting should be carried out in the early morning.