Analysis of Natural Food Composition of Fishes in Shatt Al-Arab River, Southern Iraq

A total of 1469 fishes of 39 species were caught between July 2010 and March 2011, using coastal seine net from three stations in Shatt Al-Arab River (Al-Daeir, Hamdan and Al-Fao). Environmental factors in the river were measured (water temperature (21.85±4.71ᵒC), pH (7.96±0.25), salinity (3.26±2.25 ppt), D.O.(9.15 ±1.77 mg/L) transparency (37.29±16.08cm).The dominant species in Shatt Al-Arab River was Carassius auratus which comprises 20.76% and 42.90% from total numbers and weight, respectively. The feeding intensity (8.79 - 12.37 point/fish) for all fed fishes indicates that most fishes fed with half fullness stomach at all seasons. The food contents of 593 individuals belonging to 15 species were analyzed for reliable results. Sixteen food items used to calculate standardized diet compositions and trophic levels of fishes. Plant origin food items comprise 48.54% of preponderance index, while it was 39.43 and 12.03 % for animal and organic matter food items, respectively. Shatt Al-Arab feeding index showed two peaks at spring and autumn (61.87, 59.74, respectively).While the mean value of trophic level for vegetarian fish species was 2.06 which differ significantly (F=12.14,145.01 P= 0.013,0.00) from both species which depend on detritus (1.36 ) and on animal (3.38) food items, respectively, which were also significantly different (F=350.04,P=0.00) from each other.