Dozens of dead fish have been found in the Pineios River in central Greece.
The fish were discovered near Tempe and have been collected for tests by local authorities. Members of a local environmental group said they think the fish may have been poisoned by people who wanted to collect them from the surface.
Earlier this week, hundreds of dead fish washed up on the banks of Strymonas River near Lake Kerkini in northern Greece.
Authorities said this was the result of a drought caused by a prolonged heat wave, which reduced the water level in the river and lake substantially.