The study measures the relationship between physico-chemical variables with the cell density of phytoplankton in nursery, growout and broodstock ponds of fish. This study was conducted at Natore Government Fish Farm in Bangladesh from January to June, 2012. The observed physico-chemical variables like water temperature, transparency, dissolved oxygen, pH, ammonia-nitrogen, total alkalinity and total hardness were found within the standard ranges. Phytoplankton belonging to bacillariophyceae, chlorophyceae, cyanophyceae and euglenophyceae were found among the ponds but euglenophyceae with highest abundance was recorded in almost all the ponds. Total abundance of different groups of phytoplankton was recorded as mean (±SD) cell density (cell/l) (62.77±2.16)×10 4 , (47.22±0.69)×10 4 , and (77.12±3.42)×10 4 in nursery pond, growout pond and broodstock pond, respectively. Overall phytoplankton abundance was more in broodstock pond than in others. Total phytoplankton density has exhibited significantly positive correlation with dissolved oxygen (DO) and inverse relation with water temperature, pH, ammonianitrogen and total alkalinity in case of nursery pond. For growout pond, total phytoplankton density has exhibited significantly positive correlation with temperature and transparency, and significantly negative correlation with other physico-chemical characteristics. In case of broodstock pond, total phytoplankton density has no significant relationship with any physico-chemical variables of water.

The study measures the relationship between physicochemical variables with the cell density of phytoplankton in different stages of pond – nursery ponds, grow out ponds and brood stock ponds. The study was conducted on nine fish ponds as three from each category of pond at Natore Government Fish Farm in Bangladesh, during the months of January to June in 2012. The observed physicochemical variables– water temperature, transparency, dissolved oxygen, pH, ammonia-nitrogen, total alkalinity and total hardness – were found within the standard ranges. Four groups of phytoplankton– Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae– werefound among the ponds where Euglenophyceae was recorded highest number almost in all ponds over the study period. Total abundance of different groups of phytoplankton was recorded as mean (±SD) cell density (cell/l) 62.77±2.16×104, 47.22±0.69×104, and 77.12±3.42×104 in nursery pond, grow out pond and brood stock pond, respectively. Overall phytoplankton was found better in brood stock pond than others. Total phytoplankton density has been exhibited significantly positive correlation with DO and inverse relation with water temperature, pH, ammonia-nitrogen and total alkalinity in case of nursery pond. In case of grow out pond, total phytoplankton density has been exhibited significantly positive correlation with temperature and transparency, and significantly negative correlation with others physicochemical characteristics. In case of brood stock pond, total phytoplankton density has no significant relationship with any physicochemical variables of water.

Context: Local farmers believe that the seasonal ponds and ditches which can retain water for 4 to 6 months in a year cannot be utilized for fish production but in fact such waters hold tremendous potential for culture of small indigenous fish species.Objectives: To evaluate the effects of fertilization and feeding in the growth and production of Puntius sophore culture in seasonal ponds. Materials and Methods:Six ponds were used during this study under two treatments. Two treatments such as T1 (only fertilizer) and T2 (fertilization and supplementary feeding) were run in triplicate. P. sophore was stocked in the two treatments at the rate of 15500 ha -1 after necessary pond preparation and fertilization.Results: Important physico-chemical factors viz., temperature, transparency, pH dissolved oxygen and total hardness of two treatments were found within the productive ranges. Four groups of phytoplankton were found in the ponds namely Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae and two groups of zooplankton viz. Crustacea and Rotifera. P. sophore successfully breed in both treatments. However, the number of fish harvested was 122135 ha -1 in T1 and 113335 ha -1 in T2. Yet the total production was higher in T2 (1091.40 kg ha -1 ) than in T1 (842.72 kg ha -1 ) as the individuals found in T2 gained more weight than those in T1 reflecting the effects of regular feeding. Conclusion:The study indicated that both fertilizer and feed based treatment was to improve more production than only fertilizer based treatment under seasonal pond conditions.

Sesarmid crabs are reported to dominate the Indo West-Pacific mangroves and consume huge amounts of mangrove leaves and detritus. Neosarmatium trispinosum Davie (1994) is common in the landward mangroves of the Ryukyu Islands in southern Japan. Stomach contents of the crabs collected from Okinawa, Miyako and Iriomote Islands showed that their diet consisted of mainly mangrove leaves with small amounts of sediments indicating that N. trispinosum is primarily detritivorous. The feeding preference of N. trispinosum was investigated by offering three types (green, yellow and brown) of Bruguiera gymnorrhiza leaves. Crabs were found to prefer brown leaves than the green or yellow ones. Consumption rate of brown leaves was significantly higher (p<0.0001) in cases where green, yellow and brown leaves were provided together, than when provided separately. The C/N ratio shows that the burrow sediments had C/N ratios 2/3 times lower than that of leaves, indicating that mangrove sediments could have higher nutritional value than mangrove leaves.

The experiment was conducted to determine the effect of seasonal variation on growth performance of Cyprinus carpio fry in six earthen ponds during December 2011 to June 2012 covering winter (WS) and summer season (SS , in SS respectively. Therefore, it can be concluded that mirror carp fry production was better in SS than in WS.