Some Osteological Studies of Coptodon zillii (Gervais 1848) and Oreochromis aureus (Steindachner 1864) Collected Shatt al-Arab River, Basrah, Iraq

This paper presents the results of a comparative study of the vertebral column regionalization of Coptodon zillii and Oreochromis aureus of the fish family Cichlidae. Osteological features that may prove valuable for taxonomic indications are defined, and on the basis of the material handled, their use to separate the two cichlid species. The morphological characteristics of the vertebral column of C. zillii and O. aureus allowed the separation of this bony structure into five morphologically distinct regions and the features of their specified vertebral shape. This regionalization is more complex than the classical division in truncal and caudal parts only. The vertebral length and height express a morphotype that may be linked with the cichlid mode of swimming.