Histopathological lesions of gill tissue in John's snapper (Lutjanus johnii) and Javelin grunter (Pomadasys kaakan) in the Oman Sea

Due to the direct contact of fish gills with water, these organs are highly vulnerable to environmental pollutants and are an appropriate indicator for assessing the pollutants status in aquatic environments. In this study, histopathological changes of gill tissue were carried out to evaluate the health of Lutjanus johnii and Pomadasys kaakan in the Oman Sea. 18 pieces of Lutjanus johnii and Pomadasys kaakan, with a mean total length of 22.5 ± 3.41 and 35.5 ± 4.35 cm and the average weight of 205.6 ± 22 and 512.6 ± 58.5 grams respectively, were collected by using gillnet from the three stations of Ramin, Haft Tir and Konarak in the Oman Sea. After dissection of the fish, the gill tissue was separated and stabilized in Bouin's solution. After performing the usual histological procedures, transverse sections with five microns thickness by microtome were prepared from gill tissue. Tissue sections were stained by Hematoxylin-eosin and finally examined by light microscope equipped with a digital photographic camera for the diagnosis of tissue lesions. Histopathologic results of gills show tissue lesions such as buckling of the secondary lamellae, increased mucosal secretion, edema, hyperemia, extensive gill destruction (necrosis), lamella degeneration, clubbing, hyperplasia, lamellar fusion. The lowest lesions in the gill tissue of Lutjanus johnii and Pomadasys kaakan belonged to theKonarak and Ramin Stations, respectively. Also, highest lesions of the gills were observed in Haft Tir station for both species. The closeness environment of the Haft Tir station and the proximity to the two traffic harbours of Shahid Kalantari and Shahid Beheshti can be due to this reason.