| I hear netting over the pond surface, make sure the water is a minimum of 3 feet deep (especially around the edges so it can't walk into the water), and you could use a Scarecrow or two are all good deterrents for herons. The Scarecrow is motion activated and sprays water in an arc when it detects movement.
About the rest well if your going to be gone for long periods of time you may only want to start with a couple of small, expendable koi and see how they do. The water parameters have to remain fairly stable in order for koi to flourish. Having a larger body of water will help. |