"garyjohn_99" wrote in message
ups.com...

-- We live in the countryside, although not by a river. Have so far had
suggestions of Fox, Mink and Otter - What I don't understand is why only
eat the head? Surely if an animal is hungry it would eat the whole fish -
but the bodies of the Koi were left scatered???

I've heard of urban foxes released into the countryside where they will kill
a dozen chickens in a run. Not eat any of them, just kill them. Perhaps
you've got a released urban fox ?