Effect of tank color on the survival of mud crab Scylla serrata larvae
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The survival rate of mud crab or mangrove crab Scylla serrata larvae was evaluated using black and yellow-painted tanks. About 400,000 zoea 1 were stocked in 6 tons of treated seawater. The larvae were initially fed with rotifers and subsequently with newly hatched Artemia until the megalopa stage. The larval rearing water was enriched with a combination of Spirulina powder and frozen micro-algal products that include Nannochloropsis sp., Tetraselmis sp. and Thallasiosira weissfolgii. After 15 to 17 days of rearing, the larvae successfully molted to megalopa stage. A total of 377,062 megalopae were harvested. Although the survival rate of megalopae was higher in yellow tanks (23.63± 0.03%), it was not significantly different when compared to those in black tanks (15.66±0.02%) (P=0.05).
de los Santos, M. A., Taro, T., Uehara, D., Dwight, I., & Masami, L. (2015). Effect of tank color on the survival of mud crab Scylla serrata larvae. In E. T. Quinitio, F. D. Parado-Estepa, Y. C. Thampi Sam Raj, & A. Mandal (Eds.), Proceedings of the International Seminar-Workshop on Mud Crab Aquaculture and Fisheries Management, 10-12 April 2013, Tamil Nadu, India (pp. 85-88). Tamil Nadu, India: Rajiv Gandhi Centre for Aquaculture (MPEDA).
PublisherRajiv Gandhi Centre for Aquaculture (MPEDA)
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Growth response of cultured larvae of silver therapon Leiopotherapon plumbeus (Kner, 1864) in outdoor tanks in relation to fertilizer type and fish density This study evaluated the effects of fertilizer type and fish density on early growth and survival of silver therapon Leiopotherapon plumbeus (Kner, 1864) larvae reared in outdoor tanks. In the first experiment, larvae (1.92 ± 0.09 mm total length) were stocked into nine, 4 m3 tanks at an initial density of 0.5 larvae L-1 and reared for 42 days at an ambient temperature of 28.8–30.7°C. Three treatments with three replicates each were compared: organic (chicken manure, OF) or inorganic fertilizers (ammonium phosphate, IF) applied once every 2 weeks, and the unfertilized (NF) tanks serving as the control group. Water quality, zooplankton densities, survival or growth of L. plumbeus larvae did not vary significantly in either fertilized or unfertilized tanks. Fertilization resulted in elevated nutrient concentrations, which did affect survival (2.10%–6.07%) of the fish larvae. In the second experiment, larvae were stocked at densities of 0.4 or 0.6 larvae L-1 in tanks fertilized at 4–5 days interval with OF and IF for 30 days. Growth performance of L. plumbeus larvae was affected by fish density, with significantly larger (20.04 ± 2.65 mm in total length) and higher specific growth rate (SGR; 6.97 ± 0.48% day-1) at 0.4 larvae L-1 than at 0.6 L-1. Fry production did not vary significantly between fish density treatment groups given the same fertilizer types, but survival rates were improved at 0.4 L-1. Together, production of L. plumbeus larvae in outdoor tanks can be optimized at a lower stocking density, regardless of the type of fertilizer used.
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The effect of background color and rotifer density on rotifer intake, growth and survival of the grouper (Epinephelus suillus) larvae Rotifer intake and early growth and survival of Epinephelus suillus larvae were determined in terms of rotifer visibility against the background color of rearing tanks and density. The larvae were stocked at 30 l−1 in 200-l fiberglass tanks with phytoplankton (green water). Larvae were fed rotifers at densities of 5, 10 and 20 ml−1. Growth and survival were comparable among larvae in both tan and black tanks with green water. Rotifer intake was significantly higher in larvae in tan tanks. In black tanks, the survival of larvae at Day 14 was enhanced by the high rotifer density of 20 ml−1. Rotifer intake and growth of larvae were similar at all densities.