Journal of Aquaculture Research & Development (original) (raw)

Three experiments were designed to determine the appropriate size and density for optimum growth and survival of rockworm polychaete Marphysa sanguinea in the integrated culture with olive flounder Paralichythys olivaceus in the flow-through system under controlled laboratory condition over a 13-week period. The experimental design was that 200, 400, 800, 400 and 400 worms were in T1, T2, T3, T4 and T5 for Experiment-1 (<0.5 g), 100, 200, 400, 200 and 200 worms were for Experiment-2 (<0.5-1.5 g) and 50, 100, 200, 100 and 100 worms were for Experiment-3 (1.5-2.5 g), respectively. The worm feed of T1, T2 and T3 was fish feces and uneaten feed, and that of T4 was controlled-no feed, and that of T5 was commercial feed. The polychaete worms were kept in 15 boxes (L50 × W40 × H30 cm), and bottoms of the boxes were filled with a 15~20 cm layer of substrate sediment of 50% gravel and 50% oyster shell. Thirty fishes were placed in each cubic tank (L70 × W40 × H20 cm) with 55 L water. The weight gain of rockworms (<0.5 g) in T1, T2 and T3 for Experiment-1 (<0.5 g) has shown 152.7%, 153.8%, and 140.3%, respectively. The weight gain was higher than in the other two groups, as the weight gain of rockworms in T1, T2 and T3 for Experiment-2 (0.5-1.5 g) was 51%, 30%, and 46%, respectively, and that of rockworms for Experiment-3 (<1.5-2.5 g), that is, 75%, 73, and 62%, respectively. From this result, it can be concluded that in the flow through system a small size (< 0.5 g) group of rockworms can be one of the most suitable species at the density of 2000-4000 inds.m-2 on fish feces and uneaten feed, as they can grow better than 0.5-1.5 g and 1.5-2.5 g rockworms. On the other hand, integrated results have indicated that in the flow through system around 8 g olive flounder fish was an excellent candidate to be associated with 0.5-1.5 g worms, which can grow better than a small size (< 0.5 g) group of rockworms and than 1.5-2.5 g worms at the optimum density 1000-2000 inds.m-2 polychaetes.