Broodstock development of Ornamental fishes
Continuous efforts were made to develop a broodstock of ornamental fi shes and breeding trials were also conducted during the year. A total of 90 spotted scat (Scatophagus argus ) in the size range of 65- 423 gm were maintained in two 8 ton capacity RCC tanks (20 per tank) and in an earthen pond (50 nos). The salinity was maintained at 20 to 30 ppt. During the current year, the RCC tanks were provided with re-circulated water, using sand fi lters and again re-circulated to the rearing tanks. The fi sh were fed daily with a formulated feed @ 5% body weight. Fortnightly examinations were carried out to check for parasitic infection. A fresh water bath for 3-5 minutes was found to be an effective prophylactic treatment in controlling parasites (Caligus spp.).
female fish of 426g/210mm with a mean oocyte diameter of 510 μm was administered HCG @ 500 IU/ kg body weight as two split doses over two days . LHRHa hormone was injected as the resolving dose @ 35 μg/ kg body weight. Male fish (47-310g/122-198mm), in an oozing condition were kept along with the female fish in a 1:2 ratio in the spawning tank . The male fish were also administered a similar dose of LHRHa. The female fish spawned spontaneously, after 24 hours of LHRHa administration. The mean diameter of spawned eggs was 627±6μm. However the eggs were not fertilized as the males did not respond and release milt.