Background : Contamination of the ecosystems by industrial and agricultural pollutants has been of major recent concern. Recent rapid industrialization in developed and even developing countries and the resultant high demands for industrial products has led to heavy metals pollution. The bioaccumulation of metals in food chain and ultimately in human body could exert deleterious effects on human health and especially on sperm quality and quantity. This study was conducted to examine the morphological changes and motility parameters disturbances due to mercury exposures on fish sperms.

Materials and methods : This is an experimental study on fishes' sperm. The fishes were with average weight of 1018±73 grams. The sperms were exposed to mercury with different concentration 0, 0.1, 1, 5, 10, 50 and 100 PPM. Their effects were evaluated by ultra morphological and motility parameters.

Results : The study showed that mercury concentrates had not effect on sperm, but in 5ppm or more mercury concentration, dropped of sperm tails could be observed. Motility characteristics of sperms had influenced by mercury with 0.1 PPM concentration or more.

Conclusion : The results reconfirmed that mercury toxicity may be exerted via respiratory systems inhibition, thus, ultra morphological changes may not be observed in early stage. Immotile sperm and dead sperm can not swim and find the ovum to fertilize it.