Several hundred tonnes of fish died in August in one of Hungary's largest fish farm complexes at Rétimajor, south of Budapest.
This fishpond system, with a water surface of around 800 hectares, is what remains of the former Sárrét marshlands.
Its current owner, Ferenc Lévai, privatised it in 1994 and has since been running it as a continuously developed, integrated agri-tourism estate, although its main source of income is still fish farming.
The fishpond system, made up of shallow, nutrient-rich lakes of varying depth, reedbeds, islands and muddy shorelines, provides a uniquely concentrated and hard-to-replace habitat for water birds.
The Rétszilasi Lakes and their surroundings are among the most strictly protected areas in Europe. In addition to their Natura 2000 status they are, under the Ramsar Convention, a wetland of international importance.
