FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

To increase the habitat space of giant freshwater prawns (Macrobrachium rosenbergii), 2 types (vertical or horizontal) of 3-dimensional net structures were designed. The vertical structure was assembled by 3 concentric hexagonal nets, while the horizontal one consisted of 6 three-layered triangular nets and assembled into a hexagon.Giant freshwater prawns were reared in indoor recirculating shrimp culture systems with or without the net structure. Results showed that there was no significant difference in mean body weight (p > 0.05) among the treatments of net use. However, survival rates and total weights of prawns in tanks with the 3-dimensional net structures were higher than those in the control group.Growth of giant freshwater prawns cultured in tanks (0.5 ton) with or without 2 layers of net structure at stocking densities of 10, 25, 50, and 75 prawns/m2, respectively, was tested. Results showed that there were no significant differences (p > 0.05) in mean body weight among all groups. However, better survival rates were found in those groups with the net structure, and they were significantly higher in groups with higher densities (p < 0.05).