Fish Stizostedion lucioperca, a cross between the pike and the perch. It has a grey-green back, white underside, two dorsal fins and a wide mouth with fangs. It is about 60 cm/24 in long and weighs about 7.5 kg. It is a solitary and voracious predator and lays up to 2 million eggs per year on vegetation in slow-flowing or still water.

It was introduced to Britain 1878, but because it reduces stocks of fish including perch, roach and bream, there have been attempts to control its numbers.