Finland identifies first recorded alien fish as bighead carp

Finland’s first recorded alien fish has been identified as a bighead carp, the Natural Resources Institute Finland said, according to Yle.

The fish was caught in a fisherman’s trap off Loviisa in July 2025. It was more than 90 centimetres long and weighed over seven kilograms.

The unidentified fish was sent to the Finnish Museum of Natural History for examination. Researchers from the museum and the Natural Resources Institute assessed its physical characteristics, and a genetic analysis confirmed the species in July 2026.

Species can survive Finnish winters

The bighead carp is native to the large rivers of China. It has been widely used in aquaculture in Asia, North America and Europe. The species has previously been found in nearby countries Sweden and Estonia.

The Natural Resources Institute said the fish in Finland was therefore probably an escapee from aquaculture.

Bighead carp grow quickly, reproduce efficiently and can tolerate Finnish winter temperatures.

Sanna Kuningas, a senior researcher at the institute, said the species has proved harmful as an alien species in the wild in North America. Along the Mississippi River, for example, it competes with native species for resources.