Evaluation water quality of Tigris River at the sites of Fish cages in Missan city

The current study, which extended from the beginning of November 2021 until April 2022, aimed to determine and evaluate water quality for fish farming in Missan Governorate on Tigris River, and to determine the effect of the distances between cages on fish productivity to determine the suitability of the study area to establish cages floating fish farming. In China, floating cages were found on the Qiyong River and were made of simple materials such as bamboo or reeds, tied with ropes, and fish were trapped in them and fed with leftover. In our research, five fish farms were selected on the Tigris River in Missan Governorate. The results of field measurements showed that the water temperature ranged between 13.1-23.7°C, the pH value ranged between 7.2-8.6. The water in the study area can be classified as weakly basic. The speed of the current in the study sites recorded values ranging between 0.38-0.7 m/s, the turbidity values ranged between 20.7-41.5 NTU, the electrical conductivity recorded values ranging between701-998 µSm/cm, the dissolved solids ranged between 540-618 mg/L, while the suspended solids ranged between 25.8-60.4 mg/L. The results of the laboratory examination showed that the waters of the Tigris River at the studied sites are considered to have good ventilation. The dissolved oxygen in the water was between 6.2-10.5 mg/l, while the vital oxygen requirement recorded values ranging between 0.4-2.7 mg/l, and the nutrient values that represented with nitrate and phosphate 1.58-2.48 mg/L and 0.08-0.29mg/L, respectively. The copper values were between 0.12-0.28 mg/l, the zinc were between 0.28-0.55mg/l, while the results for cadmium were between 0.0020.006mg/l, the results for lead appeared between 7.2-8.6 mg/l. Concluded from this research that the environmental load resulting from the floating cages on the Tigris River does not affect the quality of the river’s water, and that the distances between the cages do not negatively affect each other due to the speed of water currents in the area, which helps in the dispersal of pollutants and the speed of the river’s recovery.