Cephalic morphology of rainbow trout (Oncorhynchus mykiss)

Understanding the characteristics of the particular structure of fish bones, such as the skull helps to learn certain biological characteristics. Therefore, we studied the bones of the skull in rainbow trout (Oncorhynchus mykiss). In this study, 350 samples of different ages were sampled from Nowchah, a village near Mashhad. 18 samples of 30 dph were chosen to study the skull by Alicain blue and Alizarin red technique. Using this technique, toto clearing, the specimens of 1-30 dph were studied and 18 specimens of 30 dph were chosen. After that, the bones of skull and their origins were observed and then compared with other genera and species. The results demonstrated the specific characteristics in the level of species. In addition, by comparing the bones with 1-30 dph specimens, the origin of each one was identified. As a result, about 40 bones were observed, in which 18 were membranous, 19 pieces were endocondral and the other 3 were mixed. This technique would be also a good method to diagnosis the malformation and teratology in larvae as well as understanding the different effects of environment and nutrition on osteogenesis.