Germany's celebrity polar bear Knut has triggered a new controversy by fishing out 10 live carp from his moat and killing them in front of visitors.
Critics say Berlin Zoo should not have put live fish inside Knut's enclosure. But German media report that the carp were put there to eat up algae.
There is speculation that hand-reared Knut killed the carp just for fun.
A new polar bear cub - Flocke - made her public debut at Nuremberg Zoo on Tuesday, shown live on television.
The zoo is expecting up to 25,000 visitors daily, eager to see Flocke (German for "snowflake"). She has also been hand-reared, because the zoo feared her mother might harm her.
But the zoo has said it wants to avoid any repetition of "Knut mania". Knut was rejected by his mother, but Berlin Zoo decided to hand-rear him, in a controversial move.
There has been heated debate about whether cubs rejected by their mothers should be saved or whether nature should be allowed to run its course.
Knut is now more than a year old and has grown overweight.
The Frankfurter Allgemeine news website reports that Knut "senselessly murdered the carp", fishing them out, playing with them and then leaving the remains.