This study evaluated the effects of five diets (diet 1: Dried tubifex, diet 2: Artemia, diet 3: Artemia and commercial pellet feed, diet 4: Spirulina and commercial pellet feed; diet 5: commercial pellet feed) on growth, reproductive performances and embryogenesis of zebrafish Danio rerio for a period of 62 days. Significantly higher specific growth rate was found in diet 5 when compared with diet 1 but no significant difference was observed between diet 2, 3, 4 and 5. Mean weight and length gain were significantly greater in zebrafish fed diet 5 than diets 1 ‐ 4. While 100% survival was found in diet 4, the lowest level was 90.26 ± 1.06% in diet 1. Mean spawning success was significantly higher in zebrafish fed diet 5 than in those fed diets 1 ‐ 4. Mean fertilization and hatching rates were higher in the fish fed diet 3 ‐ 5 than in diets 1 and 2. Zebrafish consumed commercial pellet feed only resulted in more viable offsprings and grown better. Results suggested that commercial pellet is suitable in zebrafish culture for maximum growth and production of viable offspring in laboratory condition. Dhaka Univ. J. Biol. Sci. 26(2): 159-166, 2017 (July)

A study was performed to determine to effect of salinities (20, 25, 28, 30, 32, 35 and 40 ppt) and temperatures (20, 24, 28, 30 and 32°C) on the decapsulation of Artemia cyst. The dry Artemia cyst were hydrated up to 2 hrs in fresh water at (26 ± 1ºC) temperature with a density 0.3 g/ 50 ml water. Saline water was prepared using salt (NaCl) and hatching rate of Artemia cyst was counted after 36 hours of incubation. Highest hatching rate (72.86 ± 8.10) and (20.57 ± 2.71) % were measured in 20, 25, 28, 30, 32, 35 and 40 ppt salinities at 30, 32, 32, 32, 32, 32 and 32°C, respectively. The maximum hatching rate (89.38 ± 0.96)% was found in 30 ppt salinity at 24°C temperature and minimum hatching rate (20.57 ± 2.71) % was observed in 40 ppt salinity at 32°C temperature. Therefore, 30 ppt salinity and 24 ο C temperature could be the optimum salinity-temperature for Artemia cyst decapsulation.

Abstract:The effect of stocking density on growth of zebra fish was examined.Total five different stocking densities (5, 15, 25, 35 and 45 individuals per 2 liters of water) were maintained in triplicate for a period of 60 days. One month old zebrafish were randomly stocked into 15 tanks and fish were fed with commercial diet. The mean weight gain, specific growth rate and length gain for treatment 1 (5 fish/2liter) and treatment 2 (15 fish/2 liter) were significantly (p < 0.05) higher than treatment 3 (25 fish/2 liter), treatment 4 (35 fish/2 liter) and treatment 5 (45 fish/2 liter). The gender weight gain, survival rate and condition factor did not show any significant (p > 0.05) difference among treatments. The result of this study suggests that the stocking density of zebrafish could be 15 fish per 2 litre of water in a laboratory system with aeration.

Sperm and egg quality of catla Catla catla and rui Labeo rohita were investigated in Brahmaputra and Sarker Hatchery, Mymensingh, Bangladesh over two spawning seasons as early (March to May) and peak (June to August ). In both hatcheries, catla and rui produced nearly 90% motile sperms as well as higher sperm concentration (catla: Brahmaputra hatchery. 2533.33 ± 119.65 million mL-1 and Sarker hatchery, 2658.89 ± 76.55 million mL-1; rui: Brahmaputra hatchery, 2856.67 ± 67.57 million mL-1 and Sarker hatchery, 2811.67 ± 51.90 million mL'1), seminal pH (catla: Brahmaputra hatchery, 7.41 ± 0.06 and Sarker hatchery, 7.41 ± 0.06; rui: Brahmaputra hatchery, 7.39 ± 0.05 and Sarker hatchery, 7.35 ± 0.05) and fertilizability in catla were 88% and In rui 92% in both hatcheries in the peak season. The occurrence of opaque eggs in catla and rui was 12% and 8% in both hatcheries in the peak season, respectively. The present study points to the fact that the quality of fish sperm and egg depends on seasons Asiat. Soc. Bangladesh, Sci. 40(2): 231-241, December 2014

Zebrafish (Danio rerio: Hamilton, 1822) is a well-known model organism of biological research. Generally it is found in the fresh water ponds. However, the culture, breeding and embryonic development of wild D. rerio of Bangladesh is scarcely represented in the literature. Therefore, a laboratory experiment was conducted to study these aspects of local zebrafish. Water quality parameters for adult fish husbandry system were recorded. These were temperature (°C) 29.18 ± 1.53, pH 7.55 ± 0.144, TDS (ppm) 225 ± 11.136, (ORP) 48.93 ± 26.04, DO (ppm) 1.24 ± 0.591, conductivity (mS/cm) 0.450 ± 0.022, are resistivity (Mῼcm) 0.0026 ± 0.00049 for adult fish tanks. The parameters obtained from larvae rearing ranks were temperature (°C) 29.56 ± 0.777, pH 7.73 ± 0.421, TDS (ppm) 198.33 ± 39.627, (ORP) 51.37 ± 17.387, DO (ppm) 2.02 ± 0.694, conductivity (mS/cm) 0.397 ± 0.079, resistivity (MΩcm) 0.0026 ± 0.00044. After one month of rearing, adult male and female fishes were selected for natural breeding and spawning and obtained 87.5 ± 7.72% spawning success, 96.83±0.81% fertilization rate and 94.89 ± 0.27% hatching rate. The embryonic development for zygote, cleavage, blastula, gastrula, segmentation and pharyngula periods were observed and obtained proper development for each state at 28.5ºC. The survival rate of hatchlings was 10 - 20% up to 20 days post fertilization. The higher spawning success, fertilization rate, hatching rate and survival rate indicate the possibility and potentiality of culturing zebrafish in laboratory conditions and could be established as a model animal for Bangladeshi researchers. Dhaka Univ. J. Biol. Sci. 25(2): 139-148, 2016 (July)