Catfish: The (Gentle?) Giant Seen Increasingly In Swiss Waters

(MENAFN- Swissinfo) The catfish is renowned for swallowing up everything it comes across – should humans be worried? Swiss public television, RTS, dived into the Rhône to find out.

• Deutsch de Muss man sich vor dem Riesenfisch Wels fürchten? Original Read more: Muss man sich vor dem Riesenfisch Wels fürchten
• Français fr Doit-on craindre le silure, ce poisson géant? Read more: Doit-on craindre le silure, ce poisson géant
• Italiano it Dobbiamo avere paura di un pesce gigante di nome siluro? Read more: Dobbiamo avere paura di un pesce gigante di nome siluro

With its big head, huge mouth, and 1,500 teeth, the catfish naturally inspires a certain trepidation. Its body – flaccid and without scales – looks almost as much snake as fish. But bathers shouldn't fret: catfish don't attack humans, or at least hardly ever...

“Suddenly I felt a large pressure around my stomach which was very, very painful. I said to myself: head for safety, get back to shore,” says Alexandra, who fell victim to a catfish-biting incident in Sion, southern Switzerland, in 2011.

Back on dry land, Alexandra realised things weren't as bad as feared.“It managed to get off with a bit of my bikini,” she says.“But I wasn't really bleeding, it was mainly just chafing and painful.”

Other – very rare – incidents which have been reported elsewhere in Europe all have one thing in common: they happened between May and July, i.e. the period during which catfish reproduce, and when adults protect their nests from invaders.

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While catfish don't eat humans, they do eat (almost) everything else: crayfish, fish, zebra mussels, plants, ducks, snakes, rats, and... pigeons. It even eats itself, or rather, smaller catfish.

“This contributes to a sort of self-regulation of the species, since it has no predators once it reaches adulthood,” says Chloé Vagnon, a biologist who wrote a dissertation about catfish. Many studies have shown that the catfish has no long-term impact on other species, she adds.

More and more catfishes are expected to be found in Switzerland in the future, especially in Lake Geneva, where they are spreading fast. Catfish were already present in Switzerland before the most recent ice age, which led to their disappearance. Since then, the species has been gradually reintroduced by humans: firstly at the end of the 19th century in Lake Constance and in the three lakes around Neuchâtel, Biel/Bienne, and Murten. And then 20 years ago in the Rhône river and Lake Geneva.

There are several reasons why it has since thrived in Swiss waters: the absence of predators, climate change, and clandestine releases by certain anglers keen on sporting challenges or big trophies.

The catfish is the third largest fish in the world and the largest in Europe. In 2023, in the Italian river Po, a fisherman snagged a catfish 2.85 metresExternal link in length – a world record.

Unlike pike, catfish don't have teeth sharp enough to pierce human skin. Its mouth is made up of 1,500 tiny teeth which form a sort of rasp that it uses to grab and hold its prey.

Translated from French by Domhnall O'Sullivan

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