Broodstock development and controlled breeding of cobia Rachycentron canadum (Linnaeus 1766) from Indian seas.
Cobia, Rachycentron canadum has emerged as one of the topmost finfish species for mariculture. In India, cobia broodstock was developed and induced breeding was achieved for the first time at Mandapam Regional Centre of the Central Marine Fisheries Research Institute (CMFRI). The broodstock was developed in sea cages of 6 m diameter and 3.5 m depth. Sexes were separated about two months prior to the onset of breeding season and stocked in separate cages. During March 2010, a female with intra-ovarian egg diameter of 700 µ along with two males were selected for induced spawning. The brooders were induced with human chorionic gonadotropin (hCG) at doses of 500 IU per kg body weight for female and 250 IU per kg body weight for males. Spawning was noted after 39 h of intra-muscular injection. The total eggs spawned were estimated as 2.1 million. About 90% fertilization was recorded (fertilized eggs amounted to 1.9 million). The eggs were collected using a 500 µ mesh net and stocked in incubation tanks at varying densities. The eggs hatched after 22 h of incubation at a temperature range of 28-30°C. The percentage of hatching was 80% and the total number of newly hatched larvae was estimated as 1.5 million.