Density Effects on Survival and Growth of the Rock Worm Marphysa sanguinea Larvae by Application of Biofloc Technology

Abstract

Eco-friendly polychaete aquaculture is expected to meet the increasing demand for the rock worm Marphysa sanguinea which is considered an economically viable species. However, larva breeding of this rock worm is characterized by high mortality and low productivity. The present study was conducted to determine the optimal stocking densities of M. sanguinea larvae cultured in a biofloc technology system. Five groups of different densities, (10,000, 20,000, 30,000, 40,000 and 50,000 individual worms) of M sanguinea larvae, were reared for 100 days in a 20 L volume bottle in triplicate per density group. Results showed that there was a significant difference in survival rate amongst all treatments (P<0.05). The highest survival rate of 6.8 ± 0.6% was recorded at density group of 10,000 inds./bottle and the lowest survival rate of 2.3 ± 0.3% at density group of 50,000 inds./bottle. Mean final weight and the numbers of segments were the highest at the lowest density and the lowest at highest stocking density during 100 days of culture in biofloc technology system. Thus, as for M. sanguinea larvae, the optimal stocking density was of 10,000 inds./bottle, where they attained weight of 0.0189 ± 0.003 g by application of biofloc technology.