Confirmed Fishkill Events in Ukraine 2019–2026: An Event-Level Dataset Based on State Environmental Inspection Reports

Confirmed Fishkill Events in Ukraine 2019–2026: An Event-Level Dataset Based on State Environmental Inspection Reports documents 104 confirmed fishkill events in Ukraine between April 2019 and May 2026. The dataset was compiled from official public reports of the State Environmental Inspection of Ukraine (DEI) and its regional offices, collected through systematic web crawling of public DEI web portals. It was created to make scattered official reporting on fishkill incidents easier to find, compare, and reuse. Ukrainian source texts were translated into German for review; all released dataset fields are provided in English. The dataset is an event-level record: each row in the main file represents one confirmed real-world fishkill incident, not one webpage or administrative report. Multiple reports referring to the same incident were linked rather than counted separately. Follow-up reports, laboratory results, damage calculations, and legal or administrative updates were retained as source records but were not counted as separate events. The dataset is therefore a documented lower bound rather than a complete count of all fishkill events in Ukraine. This dataset does not claim to represent every fishkill that occurred. Coverage is shaped by reporting practices, regional portal availability, and disruptions during wartime, including occupation, infrastructure damage, and reduced administrative capacity. The dataset captures a substantial environmental signal during a critical period. Seventy-three percent of documented events occurred after February 2022, the start of Russia's full-scale invasion of Ukraine, making the dataset relevant for both environmental research and conflict-related environmental monitoring. The dominant identified cause category is oxygen depletion and organic load, accounting for 61% of events. For 32% of events, no cause could be determined from the available sources. The largest single event in the dataset is the mass fish die-off in the Seim and Desna river system in August and September 2024, involving over 31 tonnes of dead fish, attributed to organic pollution from a sugar factory in the Kursk region of Russia. Fish counts are available for 27 of 104 events; official damage figures in Ukrainian hryvnia are available for 31 events. Fourteen events are documented only through weekly DEI activity summaries, which may provide less precise timing than direct incident reports. The Zenodo package contains fishkill_events_ukraine_2019_2026.csv, the main event-level table; fishkill_sources_ukraine_2019_2026.csv, listing all 167 source URLs with relation type; and the documentation files methodology.md, README.md, and CHANGELOG.md. Quality assurance included independent AI-assisted classification comparison with 85% agreement, direct verification of all 202 source URLs, and programmatic validation of structure, dates, numbering, and links. The dataset is released under CC BY 4.0 and is suitable for environmental research, conflict-related environmental monitoring, water quality analysis, and comparative studies of war impacts on aquatic ecosystems.