Pegah Farhang - Fisheries Department, Faculty of Natural Resources, University of Tehran, Karaj, Iran
Soheil Eagderi - Fisheries Department, Faculty of Natural Resources, University of Tehran, Karaj, Iran

Study of skeletal ontogeny during early development is crucial in a successful larviculture. In this study, ontogeny of the caudal complex skeleton in Caspian kutum, Rutilus kutum, was studied from hatching up to ۵۰-day post hatching (dph). A total of ۵۲۰ larvae and fry were randomly sampled, cleared and stained for osteological examinations. The results showed that development of caudal skeleton is started with appearing hypurals ۱ and ۲ on ۴ dph and inflexion occurred on ۷ dph with formation of eight cartilaginous plates, including two haemal spines, parhypural and five hypurals, below the notochord. The results also revealed that during post flexion from ۱۳ to ۵۰ dph other structures e.g. rudimentary neural arch, second ural and anterior half of the neural arch of PU۳ were appeared. The inflexion point of tail growth pattern in R. kutum is in accordance with inflexion caudal complex, showing ontogeny of the caudal complex skeleton in agreements with its function demands during early development.

Tail, Ontogeny, Osteology, Deformity, Caspian kutum