The overall objectives of this project are to study the relationships and actions of neurotransmitters, neuromodulators, neuropeptides and sex steroids in controlling the processes of gonad maturation, spawning of gametes, settlement and metamorphosis of larvae in the tropical abalone, Haliotis asinina, and similar processes plus sexual differentiation of juveniles in the giant fresh water prawn, Macrobrachium rosenbergii. So that this basic knowledge could be use as the base for the endocrine manipulations of the above reproductive processes which could help to increase productivity of the aquaculture of these two species.