Pathological Effect Of Some Physical Properties & Chemical Pollution Of Water On Nile Tilapia

A total number of 773 apparently healthy Nile tilapia (Oreochromisniloticus) sexually mature from both sexes were used in this experiments.The experiment study the effect of some physical properties: The first experiment to study the effect of low and high water temperature where 140 apparently healthy fish were used and divided into 7 equal groups. One control group were exposed to water tetemperature. Three groups exposed to low levels of water temperatures8-12°C, 13-17°C and 18-2rC and three groups exposed to high levels ofwater temperature 38-4rC, 32-37°C and 26-31°C. The second experiment was designed to study the effect of different levels of dissolved oxygen where lOO fish were used and divided to 5 equal groups. One group as control was exposed to dissolved oxygen 5.2mg/L. Two groups were exposed to low DO in water 3.2 mg/L and 1.2mg/L and two groups exposed to high DO in water 7.2 and 9.2 mg/L.For field investigation, 12 water samples and 120 Nile tilapia fishsamples were taken from Helwan (branch of Nile river), El-Abbassa(earthen ponds that received their water supply from Ismailia canal) andfish ponds had its water supply from Bahr El-Baquar drain. Watersamples were taken from each locality every 4 months during the periodfrom January 2003 to December 2003 to determine the residues ofchemical pollutants (phenol and copper) in fish and water. The third experiment study the effect of chemical pollutants: A total number 533 apparently healthy Nile tilapia were used to determination of LCso for 72hr to phenol and Copper sulfate.Experimental studies to evaluated the effect of acute and chronic