Research on Crustaceans Fe D. Parado-Estepa SEAFDEC Aquaculture Department Tigbauan, Iloilo 5021, Philippines Parado-Estepa FD. 1995. Research on crustaceans, pp. 187-198. In: Bagarinao TU, Flores EEC (eds) Towards Sustainable Aquaculture in Southeast Asia and Japan. SEAFDEC Aquaculture Department, Iloilo, Philippines. Abstract Crustacean research at the SEAFDEC Aquaculture Department during the last three years focused mostly on the tiger shrimp Penaeus monodon. Studies were done along six problem areas: (1) developing spawning techniques for captive broodstock, (2) defining physico-chemical levels tolerable by larvae or postlarvae, (3) finding alternative feeds or fertilizers for extensive culture, (4) reducing the cost and evaluating the quality of formulated feeds for semi- intensive culture, (5) preventing and controlling disease, and (6) documenting the chemicals used in shrimp culture and their effects on the environment. To reduce feed costs, substitutes for expensive feed components were screened and the specific nutrient requirements of tiger shrimp during culture were determined. A few studies were made on other crustaceans. The vitellogenin levels during maturation of the white shrimp P. indicus were measured. The digestibility of feedstuffs was also tested in the white shrimp. Culture techniques are being developed for the mudcrab Scylla serrata in ponds, pens, and cages. Introduction Studies were conducted in 1992-1994 on three crustacean species: the tiger shrimp Penaeus monodon, the white shrimp P. indicus, and the mudcrab Scylla serrata. The mudcrab was identified during ADSEA '91 as the top priority crustacean for research and the white shrimp as another alternative species for grow-out in ponds. However, most of the research at AQD still focused on the tiger shrimp, the most important commercial species and the one beset with many problems. Studies on the Tiger Shrimp Penaeus monodon Breeding Quinitio et al. (1993) correlated the ovarian development with the morphological changes of the genitalia during the first maturation of female tiger shrimp. They identified two stages, the primordial germ cell and the chromatin nucleolus stages, during the earlier phase of maturation, in