2. MATERIAL AND METHODS

The broodfish management activity was carried out in off season in two FSMFs, one in Natore (1990–1991) and the other in Rajshahi (1991–1992). The stripped broodfish were prepared for second reproduction in Natore FSMF, in 1991. For broodfish preparation 1 bigha (1335 m2) size fish ponds were used in Natore. The water surface area of broodfish pond managed in Rajshahi FSMF was 2 bigha (2670 m2). The broodfish species used in the work are silver carp, catla, grass carp, rohu, mrigal, mirror carp and Thai sarputi.

2.1 Preparation of broodfish in off season

For comparision of the improved with the traditinal method of broodfish preparation, in addition to a pond managed with improved methodology (pond no.1), a control pond was also used (pond no.2) during winter and spring of 1990–1991 in Natore FSMF. Stocking of the two ponds was equal, but the treatment of control pond was similar to that of the other traditionally managed broodfish ponds of the farm. Because of certain administrative difficulties the fish prepared by the Project were not bred by the project experts. As a result only growth and the health condition of the broodfish could be compared in the two ponds. Only one broodfish pond (pond no.3) was managed with the improved technology in Rajshahi FSMF in 1991–1992. Other broodfish ponds of the same farm were used as control. Table 1 contains the stocking record of demonstration ponds.

TABLE 1
STOCKING OF BROODFISH IN POND

2.1.2 Pond preparation and manuring

All the broodfish ponds were dewatered and limed before stocking. Quicklime was applied at the rate of 50–70 kg/bigha for bottom treatment. After replenishing of water 150 kg cowdung, 6 kg urea and 10 kg TSP/bigha were used for pond preparation.

During rearing period mixture of 10 kg inorganic fertilizers (urea and TSP and 100 kg cowdung was applied fortnightly in traditionally managed pond (pond no. 2).

Daily manuring was carried out in ponds managed with improved technology. The daily dose of manure was 6 kg cowdung and 0.15 kg urea/triple superphosphate in pond no.1. Pond no.3 was treated with only cowdung at the rate of 5–10 kg/bigha/day.

In Rajshahi FSMF, where pond no.3 was located, the other (traditionally managed) broodfish ponds were treated monthly with 100 kg cowdung/bigha.

2.1.3 Feeding of broodfish

Table 2 shows the artificial feeds were applied in demonstration and control ponds. The ration was 1.5–3.0 percent of body weight, determined by sampling in Natore FSMF and by checking of feed consumption in pond no. 3 in Rajshahi.

TABLE 2
FEEDING COMPOSITION OF BROODFISH FEEDS USED IN DEMONSTRATION PONDS

10–15 kg duckweed was applied daily in ponds managed with improved technology (ponds no. 1 and 3). The fish in traditionally managed ponds were fed sporodically with 10–20 kg duckweed.

2.1.4 Other treatments

Argulus infection outbroke in pond no. 1 in December 1990. The fish were trated 3 times (in consecutive weeks) with Dipterex at the rate of 0.5 mg/l. Ulcerative fish desease was revealed during January 1991 in pond no. 2. The pond was treated two times with quicklime at the rate of 20 kg/bigha. Moreover, the fish were caught and kept in net, where light KMnO₄ treatment was applied. The condition of fish improved soon. No mortality occured.

Weekly partial exchange of about 5 % of pond water was carried out in pond no. 3 from February. Water was partially replenished in other ponds in Rajshahi FSMF monthly during preparation period.

2.1.5 Evaluation of management systems

The traditional and improved management system was compared and evaluated by the growth of fish in Natore FSMF. Detailed production data of broodfish were collected in Rajshahi FSMS. Breeding period and productivity of broodfish prepared in traditional and improved technology were compared.

2.2 Broodfish preparation for repeated breeding

Earlier stripped broodfish were prepared in a 1 bigha pond (pond no. 4) from 19th of June to 22nd of July 1991 for repeated breeding in Natore FSMF. (Stocking data are detailed in Table 1.) Fish were fed with artificial feed (shown in Table 2) at the rate of 5 percent of body weight. After about one month preparation ratio of ready females was determined and matured fish were bred.