CAGE CULTURE OF CARPS USING LOW COST IRON FRAME CAGES IN BAMBOO RAFT
Cage farming of fishes is a promising enterprise in open waters. Asian countries are concentrating in this farming method than other parts of the world. It is carried out in freshwater, brackishwater, as well as marine inshore areas. Now-a-days, cage culture is seen as an alternative livelihood for persons displaced by the construction of reservoirs. Cage culture is helpful in all sorts of aquaculture activities like, fry to fingerling production, fingerling to table size, or table size to marketable size production. This is an enclosed space that maintains free exchange of water with the surrounding water body. Although the cage farming of fishes assures production and profit, the capital investment in terms of cages and often make the farmers to rethink their investment. Therefore, low cost cages are thought to provide an answer to the increasing capital cost in the cage culture. The aim of the present study is to develop low cost cages that can be sued in the open waters.
Cage farming was done in iron frame cages in the reservoir of the FCRI, Thoothukudi, Catla was stocked at the rate of 0.5 kg/m3 and for Common carp it was 0.3 kg/m3. Cages were fabricated using iron frames with 3 basic designs and the details are given in Table 1. The iron frames were coated with an anti-corrosive paint to prevent rusting of the frame. Poly Propylene net screen was used. In all the cages an opening was provided in the upper part to stock and remove the fishes. Knotless nets and nylon screens have been used in the cages
Cages were fixed in bamboo rafts and PP drums were fixed for floating. Each large raft is made with 8 drum buoys and the smaller one was fitted with 4 drum buoys. The rafts were checked for their ruggedness, floatation and stability in the water. The rafts were also moored in the water and their worth for the currents in the water was also checked before installing the cages.
Wet balls were made with Ground Nut Oil cake, Rice bran, Wheat bran and Spirulina mix were sun dried and supplied to the fishes in the cages. The bio-growth parameters were assessed once in fortnight and the details are presented in Table 2.
From the present study it was found that, knot less nets of 10 mm are more suitable for the cages than knot nets that may cause the damages to the fishes. Square iron rods of 8mm size are stronger and durable in cages than 10mm MS rod frame as the later can be easily damaged by the water current. The cage farming operations have proved worthy with the production of minimum 4 kg/m3 water space with a very moderate stocking density of 0.5 kg/m3 which can be scaled up by increasing stocking density.
