Hormonal, environmental, and dietary manipulation of milkfish broodstock to enhance egg production.

The insufficient supply of milkfis fry severely limits the expanion of milkfish aquaculture. While natural spamning and hatchery production of milkfish fry have been attained recently, there is sitll a need to incease egg production from available broodstock. A number of studies geared towards this concern are currently conducted at SEAFDEC Aquaculture Department with moderate success. Chronic administration of estradiol-17B and 17A-hydroxy-progesterone to femaleand male milkfish broodstock increased maturation and rematuration rates. Milkfish kept under constant long phtoperiod (16L:8D) appeared to have prolonged gonadal development than thoes of milkfish reared under long to normal to short photoperiod. Ffrmulated diet containing 6% liquid that is feed to milkfish broodstock at a daily ration 4% of total body weight appeared sufficient for maintaning sexual maturation andspawning. Refinements in these areas canensure a better management technique that can provide maximum number of good quality eggs required by hatcheries.