Determination Range finding and median lethal concentration range (LC50 96h) organophosphatepesticide Diazinon on the Caspian Sea Bream fish (Abramis brama)

The actue toxicity test was performed instatic renewal system based on the standared method Proposed by OECD during 96 h, in which physicochemical parameters of test water including pH, dissolved oxygen and Temprature were daily monitored. to determine the lethal range of diazinon of fish a range finding test was carried out in aquariums coutaing 10 L of test solution. The acute toxicity test was then preformed in 5 treatment in triplicats. The obtained data were analyzed using probit analysis with %5 confidence limit. acording to the results, 24 h LC50, 48 h LC50, 72 h LC50 and 96 h LC50 of diazinon on common seabream was 10/974, 10/391, 9/134 and 7/316 respectively. The Maxium Acceptable Toxicant Concentration (MATC) of diazinon on common seabream was 0/073 mg/l and the Lowest observed effect concentration wich is equal to 96 h LC50 was 2.63 mg/l. The results indicated that compared to other fishes is more resistant against diazinon . in addition diazinon lethal toxicity takes place in a waide range of toxicant concentration.