| INTRODUCTION |
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A primary problem in culturing larval shrimp is food. Ideally one would feed larvae with their natural diet which consists of a wide variety and abundance of phytoplanktonic and zooplanktonic organisms. This abundance and diversity of food organisms of different sizes and biochemical composition maximizes chances for meeting all the nutritional requirements of the shrimp larvae (Leger & Sorgeloos, 1992). In the hatchery algae are added to the larviculture tanks during the non-feeding nauplius stage so that algae are available immediately upon molt into the protozoea stage. Algal species most often used are Tetraselmis chui, Chaetoceros gracilis, and Skeletonema costatum. As feeding preference changes from primarily herbivorous to carnivorous during the mysis stages, the quantity of algae is reduced. Nevertheless, a background level of algae is maintained as this may stabilize water quality. From the mysid stages onwards, Artemia nauplii of around 500 µm are fed to the larvae. For energetic benefits it is recommended that the size gap between algae and Artemia be minimized by feeding rotifers, nematodes or decapsulated Artemia cysts to Zoea II and III-stages, then swith to freshly hatched (mysis I, II and III stages) and finally to enriched Artemia for the postlarval stages. Shrimp larvae are fed brine shrimp in the larval rearing tank for about two weeks after they have metamorphosed into post-larvae. Traditionally, large amounts of ground and sieved trashfish, bivalves, snails and various dry rations were fed supplementally with Artemia after the PL5 stage. Also microencapsulated feeds were developed as replacements for these feeds. Production of quality artificial feeds requires attention to many factors, including nutrient composition, stability in water and attractiveness to the larvae. The food must provide the larvae's basic nutritional requirements, and it must be bound and coated so that it will not easily dissolve in water and cause pollution (Leger & Sorgeloos, 1992). |