a Hedayati - Department of Fisheries, Faculty of Fisheries and the Environment, Gorgan university of agricultural sciences and natural resources, Iran
h Rezaei - Department of Fisheries, Faculty of Fisheries and the Environment, Gorgan university of agricultural sciences and natural resources, Iran
f Darabitabar - Department of Fisheries, Faculty of Fisheries and the Environment, Gorgan university of agricultural sciences and natural resources, Iran

The aim of study was to investigate the toxicity effect of zinc at low concentration (10% LC50) and high doses (50%LC50) on roach (Rutilus caspicus). Roach with an average weight of 3.3 g and lengths of 4 cm were used in this work. Acclimatized fish were fed daily with a formulated feed.CaspianRoach were exposed to a low concentration of 10% LC50 and high concentration of 50% LC50 ofzinc for a period of control (0), 24, 48 and 96h static toxicity examination, operated within the tank of 400L. In 10% LC50 concentration zinc (96h) immune parameters neutrophil, monocyte and lymphocyte are not shown significant change toward control group (P> 0.05) and in 50% LC50concentration zinc (96h), immune factors lym showed significant decrease toward control but neu factor significantly increase toward control group (P<0.05). Eosino and mono did not showedsignificant correlation with zinc exposure (P> 0.05). In low and high concentrations of zinc, results showed zinc can cause changes in hematological, biochemical and immunological factors in Caspianroach; therefore, assessment of these indicators, could be useful to detect pollution of aquatic ecosystems

Blood parameters,Caspian roach,Zinc,Toxicity,Immune system,