Pond predators come in all shapes and sizes. The most common are herons and raccoons, but opossums, beavers, foxes, muskrats, and even bears have been known to visit backyard ponds. Unfortunately, the bright colours that attracted you to your fish make them more vulnerable to predation. If you don't take steps to protect your fish, you could end up with a pond full of water, but no fish.
Design your pond so one-third of it is at least 3 feet deep with steep sides.
Install motion sensor lights to scare raccoons and other nocturnal predators.
Set up a heron decoy. Herons are territorial and will usually go elsewhere rather than face the competition. Move the decoy around every few days or the herons will figure it out.
Use a motion-activated sprinkler system to blast any wildlife that comes near your pond.
Float an alligator decoy in your pond. These decoys often have lifelike movements and can scare away wildlife, even if the wild animal has never seen an alligator.
Cover your pond with netting. Netting is very effective, although not very attractive. It can be used as a short term fix until you get other methods installed.
Provide hiding spots using borders, dense marginal or floating plants, caves or tunnels. You can create hollowed-out islands with wood. Special caves can be purchased or made by cutting a large rubbish bin in half and cutting holes in the side.
Put faux koi in your pond that will distract predators and give the real fish a chance to escape.
String electric wire around the pond using insulated poles.