RELATIONSHIP BETWEEN WEIGHT AND MORTALITY RATIO OF COMMON CARP CYPRINUSCARPIOCULTIVATED IN FLOATING CAGES DURING ACUTE INCREASING OF TEMPERATURE

Abstract

Current study was conducted in 13 floating cages located in Shatt Al-Arab Riverbank at Al-Hartha District. Common carp Cyprinuscarpio of different weights (290-1700gm) and numbers (400-1047) fish/cage was cultivated in these cages. Observation wasalso taken from earthen pond at the same location cultivated with common carp, silvercarp Hypophthalmichthys molitrix and grass carp Ctenopharyngodonidella. Resultsshowed that water temperature range between 30-35 0C during May-June, 2015 and arange of 36- 38 0C during July-August, 2015 in floating cages, while in earthen pondthere were 1 0C more. Salinity don’t differ too much during experiment and rangebetween 1.5-3 ppt. Results of earthen pond revealed no fish mortality during experimentfor three species cultivated in this pond. Results appeared that fish mortality during MayJune don’t largely differed and its ranged between 0.709%-1.861% and there weren’t anyrelationship between fish mortality and fish weight. Different fish mortality during JulyAugust which ranged between 3.88% for average fish weight of 400 g and total fish massof 412 kg and 14.75% for average fish weight of 1700 g and total fish mass of 680 kg.Significant correlation (r=0.86) was found between average fish weight and fishmortality.Significant correlation (r=0.72) was also found between total fish weight andfish mortality. From previous results we concluded that there were positive relationshipbetween fish mortality and fish weight during July-August.