Management of cage fish culture

a. Maintenance of cage:

• It is essential to keep the cages clean to reduce mortality from inadequate food and depletion of dissolved oxygen.
• Sponges, algae and silt are the common fouling agents in the fresh water.
• Periodic cleaning is carried by manual brushing in-situ or the cage is removed, brushed, washed, and sun-dried.
• 2-5% of rohu can be stocked as a biological cleaning agent of fouling in cage.
• Cages, nets and frames must be checked at intervals for signs of damage, wear and tear, and repaired or replaced if necessary.

b. Growth check:

• Samples of fish should be taken at regular intervals and weighed so that the growth of socks can be monitored.
• Regular monitor of fish for diseases and changes in feeding behavior should also be done.

c. Harvesting:

• Can be done by using a large scoop net.
• Fish in net cages can be harvested by using a bamboo pole, which is slightly longer than the frame of the cage.
• Fish in cages are harvested when:

I. Have reached a marketable size.

ii. Further production is negligible.

iii. daily production will be improved by replacing the old with a new fingerling.

• The cages are harvested in two ways:

A. Partial harvest:

• Only a certain number of selected fish are removed and harvested that are larger or the unhealthy ones.
• Their removal reduces competition for food and space, and thereby allowing small fish to reach marketable size faster.

B. Total harvest:

• Total biomass of fish is removed.
• Replacing old stock with new fingerlings is done.
• The cage is restocked immediately after havest.