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chemotherapeutics to develop the proper fish period, a total of 70,510 and 44,250 GIFT fry were
health management in aquaculture. produced respectively, in freshwater and
brackishwater conditions. Finally under third
575 MIA, M.Y.; SHAH, M.M.R. & ALAM, experiment, a participatory on-farm trial was
M.J. (Brackishwater Station, Bangladesh Fisheries carried out to evaluate the production performance
Research Institute, Paikgacha, Khulna). Seed of GIFT in monoculture and in polyculture with
production and culture techniques of Genetically silver barb in coastal freshwater pond conditions.
Improved Farmed Tilapia (GIFT) in brackishwater Nine ponds were selected for three treatment
environment. Bang. J. Fish. Res., 2005, 9(1), 17-19. combinations of GIFT monoculture (T 1), GIFT and
silver barb polyculture (T 2), and silver barb
Effects of different levels of salinity on survival, monoculture (T 3), The ponds have been stocked in
–1
growth and gonadal development of Genetically April, 05 at a density of 25,000 fry ha . Fishes
Improved Farmed Tilapia (GIFT) were studied were fed with rice bran at the rate of 6% bw day'.
under laboratory conditions in glass aquarium, for In one month culture period, GIFT attained an
a period of ten weeks. The initial individual size of average weight of 16.27 g in monoculture and
the GIFT was 20.23±4.45 and the salinity levels 17.23 g in polyculture, against an average stocking
tested were 0, 5, 10, 15 and 20 ppt. The highest weight of 0.37 g. Silver barb reached an average
survival of 87.5% was found in 0 ppt and the weight of 16.62 g in polyculture with GIFT and
lowest 60.5% in 20 ppt. Though the survival 10.01 g in monoculture, against an average
decreased progressively with increased salinity, stocking weight of 3.79 g.
there were no significant differences (P>0.05)
among 0, 5, and 10 ppt (Table 1). Similar to what 576 MIAN, M.R.U. (Dept. of Agricultural
has been observed in survival, the specific growth Finance, Bangladesh Agricultural University,
rate (SGR %/day) also decreased as of 1.30, 1.24, Mymensingh). Economic analysis of carp based
1.08, 0.90 and 0.71, respectively, with the culture technologies in selected areas of
increased salinity of 0, 5, 10, 15 and 20 ppt. The Bangladesh. Bang. J. Fish. Res., 2005, 9(1), 107-
gonadal development was highest in 0 ppt with a 108.
GSI value of 3.75 and lowest of 2.01 in 20 ppt. In
the second experiment, gonadal development and Six carp based culture technologies such as, carp-
seed production performance of GIFT in pangas, carp polyculture, carp-golda, pangas
brackishwater condition were investigated for a monoculture, golda monoculture and nursery have
period of three months. Each of the three fine been selected to determine the cost and returns of
2
meshed hapas of 20 m made from nylon net was respective technologies in Bangladesh. The sample
placed in a freshwater (0 ppt) and in a brackish farmers selected for these technologies were 55,
water (10-15 ppt) pond of the Brackishwater 100, 65, 50, 51 and 55 respectively and thus the
Station (BS). GIFT of 65 g average weight from a total sample size stood at 376. The study covered 7
single cohort were stocked into three hapas at a districts of Bangladesh, namely, Mymensingh,
–2
rate of 2 m . The male vs female ratio was 1:3. Bogra, Noakhali, Comilla, Jessore, Khulna and
The development of gonad was faster with the Bagerhat. Both primary and secondary data were
higher gonadosomatic index (GSI %) of 3.85 % in used for this study. It was found that farmers used
freshwater condition than that of 2.73 % in a good number of feeds for the selected
brackish water. Within three months of the study technologies and they maintained no standard
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