Int. J. Hydrology Science and Technology, Vol. 1, Nos. 1/2, 2011 47 Copyright © 2011 Inderscience Enterprises Ltd. Incidence of Aeromonas species isolated from water and fish sources of Lake Manzala in Egypt Mahmoud M.M. Zaky* Botany Department, Faculty of Science, Port-Said University, 23rd December Street, Post Box 42521, Port Said City, Egypt E-mail: Zakymahmoud@yahoo.co.uk *Corresponding author Mohamed A.M. Salem Ismailia Wastewater Treatment Plant, KM 16 Ismailia-Suez Desert Road, Ismailia, Egypt E-mail: salemm32@yahoo.com Kenneth M.M. Persson Water Resources Engineering, Lund University, P.O. Box 201, 22100 Lund, Sweden E-mail: Kenneth_M.Persson@Tvrl.lth Saeid Eslamian Department of Water Engineering, Isfahan University of Technology, 8415683111, Isfahan, Iran E-mail: saeid@cc.iut.ac.ir Abstract: Lake Manzala situated in the east of Nile Delta, between the Damietta branch of Nile River and Suez Canal. The lake receives pollution from different sources, which make the lake polluted and eutrophicated. Samples were taken from five sites of the lake. Faecal coliforms showed the highest counts 2.2 × 10 3 cfu ml –1 and 4 × 10 3 cfu ml –1 in water in El-Kapoty and El-Mataryia areas, respectively. Aeromonas spp were counted on Endo Agar, and Aeromonas on selective Agar plates which reached the highest counts in water samples collected from Bahr El-Bakar drain (1.2 × 10 3 cfu ml –1 ) and in intestine of fishes collected from El-Mataryia area (4.1 × 10 2 cfu g –1 ). There was a correlation between faecal coliforms and Aeromonas spp in water samples. A total of 80 isolates of water and fish samples, were obtained from Aeromonas selective agar and other different selective media and identified with API 20 E system. Strains of Acrimonies sobria were found highly β-hemolytic on fresh human blood agar, as well as the extra cellular product of ECP and appeared to be destructive to the mammalian cells.