Giant catfish are becoming an increasing problem in German rivers and lakes.
Some are even becoming cannibals, with one monstrous 2.5-metre specimen even said to be eating swans in a river it has emptied of all other fish.
Ducks and swans on the Isen River in Upper Bavaria have to fear for their lives because they are being targeted by the giant fish.
Fishermen have been alarmed by the increasing number – and size – of the catfish, which have no natural predators and grow their entire lives.
“The fish are not actually known to eat members of their own species, but by now they are also doing this,” Manfred Holzner, head of the local fisherman’s association said.
Controlling their population is difficult – the fish themselves are notoriously tricky to catch, and nets are generally outlawed in the affected waters.