Development of broodstock of the green mud crab (Scylla paramamosain) was assessed under three different captive growout protocols viz. in the open fibre glass tanks (T1), in plastic boxes (T2) floating on fibre glass tanks and in plastic drawer/compartment (T3) for a period of 5 months under the Centre for Marine and Coastal Studies (CEMACS), Universitiy Sains Malaysia (USM). The male (M) and female (F) mud crab were cultured separately to maintain virginity. Suitability of both the sexes were evaluated considering the weight gain (size), survival and intactness of limbs during harvesting. Result of the present study revealed that, irrespectives of growout protocols, growth of mud crab happened following the sigmoid pattern. A noticeable intersexual weight attainment was observed with significantlyhigher (p<0.05) weight gain for the males. Meanwhile, growth was influenced by the culture protocols for both the sexes with significant (p<0.05) weight gain in outdoor tanks (M= 319.75 g, F= 246.17 g) followed by outdoor floating boxes (M= 250.50 g, F= 198.70 g) and indoor compartment (M= 246.40 g, F= 178.50 g). Survival and the proportion of intact crabs under indoor compartment and outdoor floating boxeswere significantly higher (p<0.05) than out door tank culture system. The result of the present study suggested that, outdoor growout protocol could be followed for faster broodstock development purposes to reduce the dependence on natural broodstock for hatchery operations.
Live feed is the basic food source and nutrient security for successful seed production of any commercially important aquaculture species of fishes, mollusks and crustaceans. Both plant and animal originated aquatic microscopic organisms are generally termed as live food. They are the basic food items in early stages (larval stage) of life cycle due to small sizes, easy digestibility and enriched in nutrients. The Nannochloropsis sp.; Nannochlorum sp. and Tetraselmis sp. are rich with relatively high content of essential fatty acids in comparison to other marine algae. Likelihood, the rotifer Brachionus sp. is ideal feed item for brackishwater finfish and mud crab larvae rearing due to its special features like rapid reproduction, slow movement, suitable size and easy digestion by the newly hatched larvae. The present study is the report on comparison of growth performance of live feed (microalgae and rotifer) in outdoor culture condition. The study was conducted at the hatchery complex of Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna. In outdoor culture condition the growth pattern obtained for three microalgae were Tetraselmis sp.> Nannochlorum sp.> Nannochloropsis sp. Highest average growth 6.87×106±1.97×106, 6.91×106±1.69×106 and 6.23×106±1.53×106 was observed for Nannochloropsis sp., Nannochlorum sp. and Tetraselmis sp. respectively in trial 3. Average growth of rotifer (Brachionus sp.) found highest 189±18.10 ind./ml at combined media of yeast and microalgae and lowest growth 119.67±17.60 ind./ml noticed with baker's yeast media. Nannochloropsis sp. contains more energy among all microalgae but Tetraselmis sp. carry highest level of protein. The highest level of protein 56.3±0.18% found in rotifer enriched with microalgae+fish oil and lowest protein content noticed with microalgae enrichment media. So, research finding suggests that, treatment T3 would be the best recommendations for rotifer culture.
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