GONADAL MATURATION OF CANDIDATE BROODSTOCK COBIA Rachycentron canadum  WITH  COMMERCIAL PELLETED FEED IN FLOATING NET CAGE

Fresh fish and squid feed usually use for gonadal maturation of the broodstock and candidate of the broodstock. However, the availability of fresh fish and squid feed for aquaculture activities is often not fully meet the criteria (quality, quantity, place, type and price).  Therefore, it is necessary to test the use of commercial pellet feed for gonadal maturation of fish studied. In terms of quality, the commercial pellet feed contain most of the nutrients needed.

Candidate of the broodstock is cultured fish obtained from Main Center for Marine Aquaculture Lampung. The selected fish are healthy, proportional, not defective and initial body weight (BW) ≥ 2 kg. Total fish are 27 divided by 3 groups in 4 x 4 x 4 m of net cages with mesh size of 1.5 inches. Three kinds of feed were used for each group: A. 100% of fresh fish; B. 80% of fresh fish and 20% of squid; and C. 100% of commercial pellet feed. Feed were given at satiation 1 times/day (approximately 3 % biomass). Vitamin C, E and multivitamins were given 2 times a week. The vitamin dose is 2 gr/kg of feed. Length-weight measurement and gonad maturity checks were carried out one time a month during the dark moon. If candidate of broodstock experiencing gonadal maturation, then hormone HCG 200 IU/kg BW was used to accelerate the gonadal maturation and spawning stimulation.

The best results for cobia gonadal maturation obtained from group B feed with fresh fish and squid (54.72%), followed by group C (49.31%) and then group A (47.22%).  Synchronization gonadal maturation of male and female has not always reached every month spawning, the degree of fertilization is still small (30 %).