Testing protein-walled microcapsules for the rearing of first-feeding gilthead sea bream (Sparus aurata L.) Larvae

Abstract

Two basic types of protein-walled microcapsules were developed with the 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 and development of Sparus aurata reared either with these microcapsules as the sole food source or with a mixed diet of microcapsules and rotifers from the start of feeding. Larvae fed on Type A microcapsules evacuated them practically intact. These larvae showed strong degeneration of the gut epithelium, liver and pancreas and died within two to three days after the onset of feeding. In contrast, larvae fed from first feeding with Type G microcapsules alone ingested and broke down the particles from the onset of feeding. No larval growth was observed, but some larvae were still alive at the end of the experiment (Day 13). Larvae reared with a mixed diet, including Type G microcapsules and a small amount of rotifers (0.5 rotifer mL^-1), showed in general normal development of gut epithelium. These larvae had good growth but survival 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.