TESTING PROTEIN-WALLED MICROCAPSULES FOR THE REARING OF FIRST-FEEDINGGILTHEAD SEA BREAM (SPARUS-AURATA L) LARVAE

Two basic types of protein-walled microcapsules were developed with th e aid of using different preparation techniques. One type (Type A) was spherical and hard-walled, whereas the other (Type G) was irregularly shaped and soft-walled. The present work examined the larval growth a nd development of Sparus aurata reared either with these microcapsules as the sole food source or with a mixed diet of microcapsules and rot ifers from the start of feeding. Larvae fed on Type A microcapsules ev acuated them practically intact These larvae showed strong degeneratio n of the gut epithelium, liver and pancreas and died within two to thr ee days after the onset of feeding. In contrast, larvae fed from first feeding with Type G microcapsules alone ingested and broke down the p articles from the onset of feeding. No larval growth was observed, but some larvae were still alive at the end of the experiment (Day 13). L arvae reared with a mixed diet, including Type G microcapsules and a s mall amount of rotifers (0.5 rotifer mL(-1)), showed in general normal development of gut epithelium. These larvae had good growth but survi val was reduced to one-half of that obtained under routine rearing of larvae fed on rotifers alone. Type G microcapsules appear to represent an adequate departure point for the development of an inert diet able to support larval growth in marine fish.