Histological study of gill in juveniles of Persian sturgeon (Acipenser persicus) caught in southern parts of the Caspian Sea

Fish gill is directly exposed to aqueous environmental pollutions and is one of the most important organs for studying the effects of contaminations. Therefore, this research was conducted to evaluate the histopathology of gill tissue in wild Persian sturgeon Acipenser persicus at natural conditions. A total number of 50 wild Persian sturgeonwere captured and sampled by trawling in the south areas of the Caspian Sea in Iranian waters from Astara port to Bandar Turkmen during 2009-2013. After biometry of fish, gill tissue sampling was done, fixed with Bouin's solution and transferred to histology lab. Tissue samples were dehydrated, clarified, mounted and colored based on the hematoxylin–eosin method. Microscopic studies showed some disasters such as regressive changes, progressive changes, circulation anomalies, clubbing, necrosis, lamellar fusion, hyperemia and hyperplasia in some gill tissues. Based on the obtained results, entering any pollution into the Caspian Sea water will change environmental states of sturgeons' habitat and lead to morphological disasters in gill and mortality in fishes.