World Aquaculture Magazine - March 2021

WWW.WA S .ORG • WORLD AQUACULTURE • MARCH 2021 57 stunted fish follows the lipostat model in which the compensatory growth of stunted fish stops when lost lipids are fully restored (Jobling and Johansen 1999). The priority of stunted fish to restore the depleted fat increase the nutritional quality of post-stunted fish at the end of the refeeding phase. Case Study 1: Grow-out Performance of Stunted and Normal Rohu Biju (2014) experimented with the growth performance of stunted and normal rohu Labeo rohita of the same age in earthen ponds. Stunted yearlings with an average weight of 83 ± 3 g and normal rohu with an average weight of 410 ± 11 g were stocked. Fish were stocked at 1/m 2 in six 200-m 2 ponds and fed to satiation with a floating pellet for carp (30 percent crude protein) for 150 days. At harvest, stunted rohu reached 410 g and normal rohu reached 586 g. Thus, the weight gain of stunted yearlings (327 g) was greater than that of normal rohu fish (149 g). The specific growth rate of stunted fish (1.06 percent/d) was greater than that of normal rohu (0.22 percent/d), indicating that stunted fish had better growth performance than the similar age group of normal rohu fish. A challenge study using Aeromonas hydrophilla , a major pathogen of freshwater fish, was conducted to test immune response of stunted and normal rohu fish. On the fifth day after immunization, stunted fish had a better immunological profile in terms of elevated respiratory activity, myeloperoxidase activity, lysozyme activity and globulin level than normal rohu. Overall, the study recommended fish farmers to stock stunted rohu in grow-out to achieve better production in a shorter crop duration. Case Study 2: Growth andMeat Quality of Stunted and Normal Milkfish Normal and stunted milkfish Chanos chanos growth and meat quality were assessed under field conditions in 200-m 2 earthen ponds for about 18 months (Lingam et al . 2019). The study compared three durations of stunting — 4, 8 and 12 months. At the end of the stunting phase, milkfish were 12 g after 4 months, 18 g after 8 months and 25 g after 12 months. Growth was better in 8-mo stunted fish compared to other groups during grow-out. Thus, an 8-mo stunting duration is sufficient to induce complete growth compensation in milkfish. In addition to complete restoration of nutrients in post-stunted fish, greater amounts of protein were measured in post-stunted fish than normal fish. Lower bone and higher flesh contents were responsible for the superior quality of post-stunted fish than the normal milkfish. The study recommended that stunting for eight months could be a viable option to produce quality milkfish seeds for grow-out. Conclusion Stunted seed can reach market size within a shorter duration, 4-6 months, than normal seed. Stunted seed of high quality, with high immune defense would help to increase production by minimizing the effect of pathogen infections during grow-out. The intense nutrients accretion of stunted seed during grow-out culture further increases the nutritional quality of the harvested fish. Stocking grow-out ponds with stunted seed can help to reduce operational costs of production. Notes R. Somu Sunder Lingam,* Assistant Professor and S. Anand, Tamil Nadu Dr. J. Jayalalithaa Fisheries University, Tamil Nadu, India-611002 Paramita Banerjee Sawant, Senior Scientist and A.P. Muralidhar, ICAR-Central Institute of Fisheries Education, Mumbai, India-400061 N.K. Chadha, Principal Scientist, ICAR-Central Institute of Fisheries Education, Mumbai, India-400061 K. Syamala Scientist, ICAR- Central Institute of Fisheries Education, Mumbai, India-400061 * Corresponding author: somusundarlingam@tnfu.ac.in References Ali, M., A. Nicieza and R.J. Wootton. 2003. 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