ontogenetic development of the digestive system in alburnus chalcoides larvae and juveniles

The growth of the gastrointestinal tract of the larvae and juvenile of alburnus chalcoides was studied after histological analysis using light microscopy, haematoxylineosin staining and the mouth development was scanned via electron microscopy. this study focuses on the morphology and histology of the mouth growth and digestive tract of a. chalcoides larvae to test the best weaning time for providing practical diet for fry based on the grade of their morphological aspects. it was observed that on the fifth day after hatching, the larvae mouth was opened. on the eighth day, the yolk sac was absorbed by twothirds. on the same day, food is fed manually. yolk sac was completely absorbed in 10th day. the histological base of the esophagus was formed by day 3. at day 3, the formation of enterocytes started. also, the larvae hepatopancreas was formed on 5th day. according to the results, it was observed that after 8 days onwards, larvae of these fish can have a proper diet. at this day, the size of the mouth was 84 micro;m. when the lips were formed within 20 days and for the mouth angles 45 ordm;and 90 ordm;, the food size for mouth, was 168 and 307 mu;m, respectively.