German rivers see fish die‑offs as heat wave overwhelms cooling pools

In Freiburg, cooling pools were installed in the Dreisam River to keep water below 20 °C and protect trout and grayling during a summer heat wave. Swimmers and dogs have been using the pools, stressing the fish and prompting officials to consider temporary access bans for the 250‑metre stretch where the pools are located.

Further south in Saxony, a family trout farm near Döbeln reported the loss of nine tonnes of trout after river water rose to 28.3 °C, a temperature never recorded in the Zschopau in its 51‑year history. The farm faces a total economic loss exceeding €100 000 and received no state emergency aid. Similar heat‑related fish stress has been noted in other Saxony rivers such as the Chemnitz.

Both cases illustrate the acute impact of the ongoing heat wave on freshwater fish populations in Germany.