Full-cycle aquaculture (the use of hatchery-reared fingerlings) of many grouper species is becoming more common throughout Asia. Grouper are cultured at various scales in every country of Southeast Asia — Hong Kong, Indonesia, Malaysia, Philippines, Taiwan, Thailand and Vietnam. While currently making up only about 10–15 per cent of the total trade, there is an increasing supply of full-cycle, cultured fish. The most important source countries are Taiwan, Indonesia and Thailand. Grouper culture is also ongoing in Australia and the People’s Republic of China, although the industry in these countries will not be discussed here.

In vitro activity of Sarafin® (sarafloxacin hydrochloride) was determined against 7 luminous Vibrio harveyi isolates and 3 non-luminous Vibrio species (V. parahaemolyticus, V. alginolyticus and Vibrio species) isolated from diseased shrimp (Penaeus monodon) and rearing water, a strain of V. anguillarum from diseased marine fish, 1 strain each of V. alginolyticus, V. vulnificus, and V. mimicus from diseased grouper (Epinephelus coioides), and V. alginolyticus from diseased seabass (Lates calcarifer). Bacterial susceptibility was expressed as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The MIC and MBC values obtained for all V. harveyi isolates ranged from <0.3 to 1.25 µg/ml. For the non-luminous Vibrio species, MIC and MBC values ranged from <0.08 to 1.25 µg/ml. In vivo tolerance levels (24 h static bioassay) of larval and postlarval stages of P. monodon for Sarafin® were <10 µg/ml for nauplii, mysis, and postlarvae and ≤1 µg/ml for zoeae. Morphological deformities in the carapace, rostrum, and setae were noted among larvae exposed to >50 µg/ml Sarafin®. These results indicate that Sarafin® is a potential candidate as a chemotherapeutic agent against luminous vibriosis in P. monodon.

Straminipiles are common inhabitants of marine, estuarine and freshwater aquatic environments. In mangrove habitats, halophytophthorans and thraustochytrids are abundant, both in tropical and sub-tropical areas. Their abundance is attributed to their wide tolerance to environmental parameters such as salinity and temperature, and their ability to produce abundant zoospores. Fallen mangrove leaves supply the bulk of organic material in any mangrove habitat. Straminipiles are one of the initial colonizers of fallen mangrove leaves. The ability of their zoospores to respond chemotactically to nutrients released by the leaves, and to attach firmly on the substrata surface by the release of adhesive materials, make them highly competitive in the colonization process. Thus, they are reported to play significant role in the microbial degradation of fallen mangrove leaves. Moreover, these organisms, especially thraustochytrids, are producers of high amounts polyunsaturated fatty acids (PUFAs). Therefore in the degradation process, they consequently enrich the nutrient content of the leaves for the benefit of other organisms at higher trophic levels, making mangroves an excellent nursery grounds for many fish and crustacean species. Some species of thraustochytrids are also used in the commercial production of PUFAs, for use in aquaculture specifically in larval rearing of marine fish and crustaceans.

The significant role of aquaculture in providing food security has been recognized, not only through its contribution to food supply, but also through the promotion of economic and social well-being. Aquaculture is also considered as a relatively recent and underdeveloped sector as compared to agriculture and animal husbandry, and there is a huge, unfulfilled potential in many countries, particularly in the region. The recently concluded ASEAN-SEAFDEC Conference “Fish for the People” highlighted the importance of sustainable fisheries for regional food security, and the need for comprehensive and cooperative efforts, resolutions and plan of actions among all stakeholders. With the projected shortfall in the supply of fish and fishery products to meet the demands of an ever-increasing population, aquaculture is looked upon as a sustainable source of renewable food resources. One of the main programs of the SEAFDEC Aquaculture Department (AQD) is geared towards the development of sustainable aquaculture that is technically feasible, economically viable, environment-friendly, and socially equitable. An important subprogram is the development of environment-friendly aquaculture technologies and practices. The objectives of the subprogram are: 1) to develop and promote efficient aquaculture systems and designs for maximum sustainable productivity; 2) to devise and determine appropriate design, equipment, and operation and management practices that optimize utilization of resources and inputs, minimize adverse impacts on the environment, and sustain biological/ecological diversity; 3) to demonstrate, verify, adopt, refine, and promote proven aquaculture technologies and practices; and 4) to advance the social, economic, cultural, and policy importance of the aquaculture sector at the local, national, and regional level. At present, the main research areas are in nutrient dynamics of aquaculture systems, feed and waste management, development of culture systems, including bioremediation strategies, conservation and sustainable utilization of resources for aquaculture, and socio-economic and policy issues in aquaculture. In addition, verification and refinement of developed aquaculture technologies, in support of re search and training activities, are conducted to explore the potential of aquaculture technologies for commercial adoption and demonstrate appropriate technologies and responsible aquaculture practices. The paper presents an overview of current research activities by the author, and with involvement of other researchers at SEAFDEC AQD, including future plans under this and related programs.

The Asian catfish, Clarias macrocephalus is a native but fast disappearing species in the Philippines. It is locally named as hito to Tagalogs, paltat to Ilocanos, pantat to Cebuanos and Ilongos, and Ito to Pampangueños. They are called catfishes because they posses whisker-like structure near their mouth called barbells. Among the Clarias species Clarias macrocephalus is preferred because of its tender and delicious meat. Many people believed that the disappearance of the native catfish is due to interbreeding with Thai catfish, Clarias batrachus and the rampant use of pesticides in the ricefields that "poison" the breeding grounds of this species. At SEAFDEC/AQD, standardized techniques were developed in the laboratory for breeding and seed production of this species. Verification studies are on going on nursery techniques in tanks and ponds and grow out culture in ponds. The topics to be discussed are mostly based on SEAFDEC's research studies and hands-on experiences on the native catfish Clarias macrocephalus.