Induced breeding of crucian carp, Carassius carassius was conducted in order to determine the optimum dose of pituitary gland (PG) hormone. The research was done at the hatchery of the Freshwater Station, Bangladesh Fisheries Research Institute, Mymensingh. The study was consisted of four different doses of PG treatments (T 1 , T 2 , T 3 and T 4 ) with three replications of each. In the experiment single dose was used for T 1 while double dose used for T 2 , T 3 and T 4 to evaluate the efficiency of PG hormone on ovulation, fertilization and hatching rates of C. carassius eggs. Single dose of 6.0 mg PG kg -1 body weight (bw) of female fish had no ovulatory response. The double dose in case of female fish in T 2 at the rate of 6.0 mg PG kg -1 bw (1 st dose 1.0 and 2 nd dose 5.0 mg PG kg -1 bw at 6 h interval) and 2.0 mg PG kg -1 bw of male fish (single dose during the time of 2 nd injection of female) in January showed better results in terms of ovulation (96.52±1.53%), fertilization (90.35±1.67%) and hatching rates (78.65±2.84%) compared to other treatments. Considering ovulation, fertilization and hatching rates the double dose of 6.0 mg PG kg -1 bw of female and single dose of 2.0 mg PG kg -1 bw of male can be used in induced breeding of C. carassius during January. The findings of this study indicated that induced breeding of C. Carassius is successful through PG extract and might be useful for large scale seed production in the hatchery operation.

A study was conducted from July 2013 to June 2016 on production rate, quality, and color of pearl, cultured at Trishal, Fulbaria and BFRI (Bangladesh Fisheries Research Institute) of Mymensingh region. Freshwater pearl producing mussel, Lamellidens marginalis was used in this experiment. Eighty mussels per decimal were stocked in integration with fish culture. Three ponds from three locations were used. The area of each pond was 40 decimal having water depth of 1.5m in Trishal, Fulbaria and BFRI respectively. Water temperature, pH, Ammonia, Dissolve oxygen, Alkalinity, Ca2+ and Phytoplankton (× 103) ranged from 25.37-28.730C, 6.2-7.92, 0.02-0.3mg/l, 5.09-6.08mg/l, 100.17-191.50, 15.31-25.87and 48.99-63.45, respectively. Survival rate of the operated mussels were 30.62%, 34.62% and 40.25%, respectively. After 3 years of rearing, 53%, 76% and 93% pearls containing mussels were harvested from Trishal, Fulbaria and BFRI respectively. After final harvesting total pearl production, its quality and color were observed and found better at the location of BFRI, followed by Trishal and Fulbaria. Research study concluded that, the quality of pearl depends on intensive care, proper management, suitable water quality parameter, sunlight penetration, food availability and soil quality of the culture pond.  J Bangladesh Agril Univ 17(3): 424–429, 2019

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The study was conducted to evaluate the effects of pH on the filtration rate of freshwater pearlmussel Lamellidens marginalis under laboratory conditions. Three treatments were used in triplicate;treatment 1 (T1) at pH 7.5, treatment 2 (T2) at pH 8.0 and treatment 3 (T3) at pH 8.5. Ten mussels werestocked in each aquarium with continuous aeration. After 48 hours, 40 ml eutrophicated water having 34.75 x105 to 36.0 x 105 cells/ml of phytoplankton were provided in each aquarium. Initial concentration ofphytoplankton was 14400±360.55, 13900±360.55 and 14133± 404.14 cells/ml, whereas the finalconcentrations were 10300±100.00, 8300±200.00 and 10333±57.73 cells/ml in T1, T2 and T3, respectively.The reduction rate was consistently lower in T2 when compared to other treatments. Mussels of T2 (pH 8.0)exhibited significantly higher filtration rate (p<0.05) over T1 (pH 7.5) and T3 (pH 8.5) at all sampling times.The minimum filtration rate 58.03±32.79 ml/mussel/h was found in T3 after 1 h exposure, whereas thehighest filtration rate 110.94 ± 21.68 ml/mussel/h was obtained in T2 after 2 h exposure. The resultsconcluded that the pH has a clear effect on feeding habit of freshwater pearl mussel and pH 8 providesenvironment friendly to maximize the filtration of L. marginalis.