Marbled catfish confirmed in Finland for the first time, raising ecological concerns
Finnish authorities have confirmed the presence of the marbled catfish (Silurus glanis var. marmoratus), an invasive species, in the country’s waterways for the first time. The Natural Resources Institute Finland (Luke) identified the species through genetic analysis after two separate observations last July.
The first specimen was caught in a fisherman’s trap off the coast of Loviisa, measuring over 90 centimeters in length and weighing more than seven kilograms. The fish was initially sent to the Finnish Museum of Natural History for examination before Luke confirmed its identity (Ilta-Sanomat). A second observation occurred shortly afterward when a marbled catfish was recorded on a camera monitoring a fishway in the Kymijoki River dam (MTV Uutiset).
Origin and ecological risks
The marbled catfish is native to large rivers in China but has spread globally due to its use in aquaculture across Asia, North America, and Europe. According to Luke, the species has previously been detected in Sweden and Estonia, indicating its ability to thrive in the Baltic Sea region (MTV Uutiset).
Luke has expressed concern over the species’ potential impact on Finland’s native fish populations. The marbled catfish grows rapidly, reproduces efficiently, and tolerates cold winter conditions, raising fears of ecological disruption. In North America, it has already been classified as a harmful invasive species (Ilta-Sanomat).
“The monitoring camera captured the marbled catfish swimming upstream, making this observation particularly concerning,” said Luke’s senior researcher Sanna Kuningas in a press release (Ilta-Sanomat). The species’ ability to migrate upstream suggests it could establish itself in Finnish rivers, further threatening local ecosystems.
