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Production potential of shingi, Heteropneustes fossilis and koi, Anabas testudineus in polyculture were assessed at a stocking density of 2, 47,000 and 3, 70,500 ha -1 , respectively in treatment T1 and T2. Monoculture of H. fossilis and A. testudineus was designed at a stocking density of 2, 47,000 ha -1 in treatment T3 and T4, respectively. Culture period of shingi was 120 days and koi was 100 days in all treatments. All fingerlings were of the same age at stocking, with a mean weight of 2.54±0.08 g for shingi and 0.50±0.01 g for koi, respectively. Commercial fish feeds (30.0% crude protein) supplied at the rate of 100 to 5% of total biomass twice daily. Fish production in treatment T1, T2, T3 and T4 were 18,803±111, 12,388±115, 10,042±5 kg ha -1 day -120 and 22,176±7 kg ha -1 day -100 , respectively. The feed conversion ratio (FCR) was significantly (P<0.05) lower in T4 than that of the other three treatments. The net financial benefits incurred from treatment T1, T2, T3 and T4 were Bangladeshi Taka 17, 65,769; 6,691; 15,83,990 and 16,29,409 BDT ha -1 , respectively. The mean differences of gross yields and net benefits among different treatments were significant (P<0.05). The polyculture technology of shingi and koi, and monoculture technology of koi may help to meet the dietary needs and improve the socio-economic status of the people of Bangladesh.

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Growth and survival of Pangasianodon hypophthalmus was assessed in relation to feeding of different feeds for a rearing period of 21 days. The experiment was designed with 3 treatments and 4 replications. The nursery ponds were stocked at a density of 0.6 million hatchling/ha with 3days old P. hypophthalmus. The highest growth performance, survival and production of the fry was found in treatment T in terms of length, weight and number, where sustainable nursery management was 1 implemented and egg yolk, mustard oil cake, nursery feed and Tubifex Chop were supplied. Poor growth performance and survival was recorded in treatment T where nursery management was poor 3, with insufficient food supply. The highest average growth was recorded at 5.66±0.55 g, SGR 12.24±0.68, FCR 0.68±0.01and survival rate 52.15±0.78% in the treatment T. The treatment (T) 1 1 also showed highest economic return (Bd Tk. 290543/ ha) than that of treatment T and T. The 1 2 physico-chemical factors were found to be in optimum level for fish culture.

Successive developmental stages of both male and female gonads and estimation of gonado-somatic index (GSI) of Puntius sarana (Hamilton 1822) were investigated over a two year period (October 2002 to September 2004). From the histological analysis, four developmental stages such as spermatogonia, spermatocytes, spermatids and spermatozoa were identified in testes. Three developmental stages of oocytes such as ogenesis (oogonia, early perinucleolus stage and late early perinucleolus stage), vitellogenesis (early vitellogenic oocytes, advanced vitellogenic oocytes and maturation stage) and atretic stage were distinguished in ovaries. Maximum mean gonad weight was recorded in June for both females (8.92±0.01 g) and males (4.48±0.21 g). The testes at early development stages between October and March contained mostly spermatogonia, spermatocytes and spermatids, although a small amount of spermatozoa was also found in late March. The mature testes began to develop in early April and were prominent from May to September. Highest percentage of oogonia in the ovary was recorded in the month of November; while the highest percentages of early perinucleolus stage and late perinucleolus stage were recorded in the month of January. Vitellogenesis (matured oocytes) occupied the most areas of the ovaries which were observed from May to mid September but was prominent in June. All oocytes did not mature at the same time. Only the matured oocytes ovulated in the spawning period while immature oocytes gained maturation under way of vitellogenesis and released at the second spawning time in the months of August and September.

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