My goldfish have disappeared - about 10 of them overnight. I still have 2 large Koi although 1 rarely comes up to the top and lots of smaller fish that swim really fast. I realise a heron may have got them but all in one go and at night??!! I haven't had them that long as i inherited the pond in a house move - do they hide sometimes or when having babies as lots of babies have also appeared recently. They were happily swimming on monday but no sign since tuesday - any suggestions?