To the horror of onlookers, once cuddly Knut, now 16 months old, killed 10 live carp swimming in the moat surrounding his enclosure.

The fish were placed there to keep the water clean by eating algae growing below the surface.

Visitors complained after Knut started fishing the carp out of the water with his paws and throwing them around the enclosure before leaving them to die.

Zoo biologist Heiner Kloes said Sunday, April 6, that no more live fish would be released into the moat. He said the carp were meant to act as "cleaners" and not as food.

Dead fish form a regular part of the polar bear's diet. Under German laws live vertebrates like fish are not allowed to be fed to animals.

Knut attracted global attention as a cub when his keepers raised him by bottle after he was abandoned by his mother.

Millions of visitors have come to see him since, enabling the zoo to reap record profits through ticket sales and merchandising.