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vol-37Impact of drainage effluents on the condition of Cichlid (tilapias)
fish in Lake Edku, Egypt
Mohamed A. Sayed Ahmed
Fish Physiology Lab., National Institute of Oceanography and Fisheries (NIOF), Al-Anfushi,
Kayet bey, Alexandria, Egypt. Tel: +203-4807138, +203-4807140,
Fax: +203-481174, P.O. Box: 21556. E-mail: [email protected],
Web site: www.niof.sci.eg,
E-mail: [email protected]
Received 1th January 2011, Accepted 29th January 2011
Abstract
A total of 1011, 959 and 830 Cichlid fish, Oreochromis niloticus, Tilapia zillii, Sarotherodon galilaeus and
Oreochromis aureus were monthly collected from El-Boughaz area, outlets of Edku and Bosily Drains and outlet of
Barsik Drain, north, east and south of the Lake Edku, during the period 2001-2003. The length-weight relationship
(LWR) was significantly correlated, the values of coefficient of determination r
2 were very close to 1.0 and
significant at 0.05 level and the slop b significantly differs from 3 (F = 7.072, P < 0.05) for all fish species from the
three areas. All fish species showed slightly positive allometric growth. The averages of relative condition factor Kn
for all fish species from the three studied areas were found to be equal 1.0 and the averages of allometric condition
factor Ka were 1.4, 1.3, 1.0; 1.3, 1.4, 1.3; 1.5, 1.4, 1.4 and 1.3, 1.3, 1.0, meanwhile, the values of natural mortality
M were 0.7481, 1.1058, 0.5843; 1.2379, 1.1122, 0.8786; 0.7404, 1.3506, 1.0446 and 0.9786, 2.0558, 0.4087 for O.
niloticus, T. zillii, S. galilaeus and O. aureus, respectively. Statistically, Ka showed insignificant deference either
depending on areas (F = 2.59 , P = 0.129) or on species (F = 1.67 , P = 0.250), while, M was significant (F = 4.31 ,
P < 0.05) depending on areas and insignificant (F = 0.281 , P > 0.05) depending on species. The condition of fish
species at the three studied areas was found, approximately, comparable. There is no difference of the stress effect
on fish species from one area to another of Lake Edku.
Keywords: Lake Edku, Cichlid fish, fish condition, natural mortality.
