1. A sudden, widespread death of fish in a body of water, typically caused by pollution, low oxygen levels, disease, or toxic algae blooms.
Usage: Usually plural or used as a mass noun; can refer to a single event or multiple occurrences

Examples

• The fishkills in the river were caused by industrial waste dumped upstream.
• Scientists are investigating the recent fishkills affecting the estuary.
• Algal blooms have led to massive fishkills along the coast this summer.
• The fishkills devastated the local fishing industry.
• Water quality tests revealed that low oxygen levels triggered the fishkills.
• Environmental groups are working to prevent future fishkills in the lake.