The Shatt al-Basrah Canal, a brackish artificial waterway in southern Iraq, experienced a fish mortality event in August 2021, raising serious environmental and socioeconomic concerns. This study documents field observations, photographic evidence, and in situ water-quality measurements collected during the event to characterize environmental conditions associated with the mortality and situate them within the context of long-term ecosystem degradation in the region. The event coincided with critically low dissolved oxygen concentrations (1–2.5 mg L−1), elevated summer water temperatures (31.2–31.6 °C), high total ammonia nitrogen levels (1.88–2.2 mg L−1), and brackish salinity (17.4–23 ppt), reflecting strong anthropogenic influence and limited hydrological flushing. These stressors occurred in areas receiving untreated wastewater inputs and affected both native and non-native fish species tolerant of estuarine conditions. Comparison with documented fish-kill events from Kuwait Bay and other parts of the northern Arabian Gulf indicates similar environmental settings characterized by hypoxia, organic enrichment, and summer thermal stress. The 2021 mortality event suggests how acute ecological deterioration may arise in chronically degraded brackish systems and underscores the need for continuous water-quality monitoring, improved wastewater treatment, and proactive management to reduce the risk of recurrent fish kills in Iraq’s vulnerable aquatic ecosystems.
Naser et al. (Tue,) studied this question.