Breeding and larval rearing of the milkfish Chanos chanos (Pisces: Chanidae)

Contribution No. 11 of the Aquaculture Department, Southeast Asian Fisheries Development Center, P.O. Box 256, Iloilo City 5901, Philippines.Two sexually maturing female milkfish were captured in April 1977 and induced to spawn by means of acetone-dried Pacific salmon pituitary powder. The eggs were fertilized and incubated and the resultant young reared to 74-day old, 11 cm long fingerlings. Newly fertilized eggs averaged 1.16 mm in diameter and each had a narrow perivitelline space containing several cortical granules which disappeared within a few minutes. The yolk was slightly yellowish, devoid of oil globules and very finely granulated. Embryonic development was very similar to that of other pelagic fish eggs and hatching occurred between 35 to 36 hr at a salinity of 32 ppt and a temperature range of 28.4-29.2°C.This study was partially supported through a grant to the SEAFDEC Aquaculture Department by the International Development Research Centre of Canada, under Project No. 3-P-74-0146

Induced spawning and larval rearing of grouper (Epinephelus salmoides Maxwell)

Excerpt from The First Asian Fisheries Forum. Asian Fisheries Society, Manila, Philippines.Broodfish of grouper (Epinephelus salmoides ) were induced to spawn by hormonal induction. The hormones used for this experiment were HCG + pituitary gland (PG) and LRH-a. The results showed that at dosages of 500 IU HCG + 3 mg of PG per kg of fish for first injection and 1,000 IU HCG + 3 mg of PG per kg of fish at the final injection at an interval of 24 hours, the treated fish spawned naturally in a spawning tank 12 hours after the final injection. At lower dosages of 500 IU HCG + 3 mg PG at 12-hour intervals or 500 IU HCG + 3 mg PG at 24-hour intervals or using 10 mg LRH-a at 12-hour intervals, the eggs can be artificially fertilized only by stripping. The larval rearing experiment was conducted in a 250-l fiberglass tank at the stocking density of 2,500 larvae per tank. Feeds used in this experiment were: (a) Isochrysis + sea urchin eggs; (b) Isochrysis + Brachionus ; and (c) Tetraselmis + Brachionus . The results showed that newly hatched larvae fed with Isochrysis mixed with sea urchin eggs and then Brachionus from day 10 had the best survival rate (9% at day 30)