I live in the UK, in the Midlands. Over the last week I've lost 3 of my pond fish. The garden pond is covered with fine, galvanised mesh. Up until now I've had no predator problems. I don't think it could be an heron or any form of bird, I've dismissed a fox or cat because, it would be difficult for these animals to penetrate the mess & these animals would have move the mesh. The mesh as not shifted, yet I've suffered fish loss. (There are no water snakes or reptiles in my area of the country) It is a predator taking only one fish at a time & leaves no evidence behind. I thoughts are could it be a rat? Could a rat enter a pond, swim & catch fish?