Relationship between weight and mortality ratio of common carp cyprinuscarpio cultivated in floating cages during acute increasing of temperature

الملخص EN

Current study was conducted in 13 floating cages located in Shatt Al-Arab River bank at Al-Hartha District.

Common carp Cyprinuscarpio of different weights (290-1700 gm) and numbers (400-1047) fish/cage was cultivated in these cages.

Observation was also taken from earthen pond at the same location cultivated with common carp, silver carp Hypophthalmichthys molitrix and grass carp Ctenopharyngodonidella.

Results showed that water temperature range between 30-35 0C during May-June, 2015 and a range of 36- 38 0C during July-August, 2015 in floating cages, while in earthen pond there were 1 0C more.

Salinity don’t differ too much during experiment and range between 1.5-3 ppt.

Results of earthen pond revealed no fish mortality during experiment for three species cultivated in this pond.

Results appeared that fish mortality during May- June don’t largely differed and its ranged between 0.709%-1.861% and there weren’t any relationship between fish mortality and fish weight.

Different fish mortality during July- August which ranged between 3.88% for average fish weight of 400 g and total fish mass of 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 fish mortality.Significant correlation (r=0.72) was also found between total fish weight and fish mortality.

From previous results we concluded that there were positive relationship between fish mortality and fish weight during July-August