Studies On The Nutritional Physiology And Development Of Artifical Microdiets Of Tongue Sole (Cynoglossus Semilaevis) Larvae And Post-larvae

The tongue sole, Cynoglossus semilaevis is a Chinese inshore species with a great potential for aquaculture. In spite of great commercial interest, there is limited information about the biology, nutritional requirements or techniques for intensive rearing of larvae of this species and weaning is still identified as a bottleneck for sustainable production. The aim of this work is to supply reference for the knowing about nutritional requirements and the manufacture of artificial microdiets through studying digestive physiology in different developmental stages of tongue sole and development of prepared microdiets. The results of this study are summarized as follow.ExperimentⅠ.Histological changes of the digestive system and its associated glands were studied in tongue sole Cynoglossus semilaevis from the first day (first day post-hatch dph) until 30 dph. Specimens for this study were hatched from artificially spawned broodstock and maintained in the indoor cement tanks (20.0~22.0℃). At mouth opening (3 dph), lengthening of the digestive tract, mucosae differentiation and pancreas and liver appearance are the most apparent elements. The yolk is gradually resorbed and disappeared at 5 dph., while the digestive tract was differentiated in five portions: buccal-pharyngeal cavity, esophagus, stomach, anterior and posterior intestine. The larvael digestive system is morphologically ready to process external food at this time. During the following period of independent life the most noticeable events occurring are an increase in mucosal folding, cellular differentiation in the luminal epithelia, gut segmentation and looping. Thus, these digestive tract and associated glands become mature gradually and complete the morphological digestive features characteristic with increasing age and feeding...