Not only do pond keepers have to keep their Fish alive through care water quality monitoring, a healthy diet, adequate filtration etc. they must also be mindful of native predators, most commonly Herons and Seagulls. Herons are known for completely clearing ponds of Fish, even Koi are susceptible to predation. There are several deterrent-based products available on the market; shiny balls with eyes painted on them, Heron statues, laser and alarm systems and many more. Unfortunately, Herons are smart animals and come to learn that these products are not a threat to them and will often overlook them. Ultimately the best solution is a physical barrier whether than is a wire fence around the perimeter of the pond, netting across the pond or even electric fencing around the pond. A physical barrier will create a fool proof way of stopping the Herons from wading into the pond to collect their lunch.
Seagulls on the other hand although not known for clearing ponds will give it good go trying to peck at the Fish very rarely resulting in a takeaway meal for them but leaving your Fish with open wounds often leading to infection such as ulceration if left unsupervised or treated. The same goes for Seagulls as it does for Herons, a physical barrier is your best choice however in this case Seagulls approach the water from above so any wire fencing will not work, netting or a cover over the pond is a must.
