2025, Vol. 6, Issue 2, Part A

The Tigris River, a crucial transboundary waterway in the Middle East, has undergone significant environmental degradation due to escalating pollution from industrial, agricultural, and domestic sources. Flowing through Turkey, Syria, and Iraq before merging with the Euphrates to form the Shatt al-Arab, the river supports diverse ecosystems and provides essential services—including irrigation, drinking water, and fisheries—for millions of people.

Over recent decades, rapid urbanization, unregulated industrial growth, and intensified agricultural practices have severely compromised its water quality. Industrial effluents contaminated with heavy metals (e.g., lead, cadmium, mercury, and chromium), agricultural runoff containing organochlorine and organophosphate pesticides, and untreated municipal sewage laden with pharmaceutical residues, endocrine disruptors, and organic waste have all contributed to the progressive decline in water quality.

Fish populations in the Tigris River serve as key bioindicators of ecosystem health due to their continuous exposure to contaminants via gill respiration, dietary intake, and dermal contact. Native species such as Barbus luteus, Cyprinus carpio, Tinca tinca, Carassius auratus, and Barbus sharpeyi have been extensively studied for their physiological and histopathological responses to pollution.

This review synthesizes current scientific evidence on the physiological, histopathological, biochemical, genetic, and behavioral effects of pollutants—including heavy metals, pesticides, pharmaceuticals, and organic waste—on fish species in the Tigris River. It highlights the complex interactions between contaminant types and biological systems, underscoring the critical role of fish as sentinel species in environmental monitoring programs.