Planning a new garden pond then get your Heron in early
If you are planning to build a new garden pond with some fish then your first move should be to establish a statue of a heron ideally even before you start digging the pond. A Heron can clean out your pond of fish within a matter of hours but they are very territorial and will not normally intrude on other herons patch so by adding a statue of a heron before you add the fish serves as a mark that your pond is taken already by an existing heron.
If you have already suffered an attack by a heron on your fish it’s often too late to add a heron statue to discourage further attacks