Normal and abnormal osteological development of caudal fin in Sparus aurata L. fry

Normal osteological development of the caudal fin in gilthead sea bream is described at the larval and juvenile stages. It was used as a standard for the study of a sea bream larval population with characteristic osteological deviations which give rise to abnormal juveniles. Normal specimens were reared under extensive rearing conditions, and abnormal specimens under intensive rearing conditions. The first hypural elements appearing in the abnormal preflexion larvae were deformed and displaced. With development, all elements related to the caudal region (parhypural, hypuralia, epuralia, vertebra centra, neural and haemal processes) formed abnormally. The abnormalities were extra-numerous elements, fusions, deformities and displacements of the elements.