Every fall we receive phone calls and emails from upset customers whom have lost fish to pond predators. We can sympathize and know first hand that terrible feeling they have when they realize their pond is now a sushi bar. Herons, Egrets and raccoons are the most popular culprits in our area but there are others to watch for too. Otters, opossums, foxes, bobcats (if you are in a rural area), snakes, snapping turtles and even large bullfrogs will eat your Koi and Goldfish.
I know what you are thinking, you have never seen a heron near your pond and most likely, you never will. They will wait until there is no movement near the pond to attack. Herons are extremely patient and once they find your pond they will return on a daily basis until they have picked off every fish. If your fish are disappearing but there are no signs of disruption, you have a Heron or Egret visiting your pond. These large birds will swoop in and take the fish with them, or if the fish is too large, they will leave it by the side of your pond. Remember in the fall the birds are migrating and the Koi are slowing down making them easier prey.
Raccoon damage is easier to detect. They love to make a mess. 
You will see muddy footprints around the pond, your plants will be torn up, pots knocked over or broken and rocks knocked into the pond. Most importantly you will find fish bones. Of course, raccoons are nocturnal so you most likely will not see them either. Otters and Snakes are a bit less noticeable and they have no problem feasting on your Koi even if you are home.
There are several options to help prevent fish loss:
- Net the pond: This will work for birds, raccoons and even otters if the net is secure enough. Also helps to keep leaves out of the pond in the fall.
- Install Koi caves: Caves will provide your Koi a feeling of security giving them a place to hide from predators and the summer sun.
- Install decoys like floating alligator heads, mirrored balls. These inexpensive items may or may not work. Herons are not only patient but also smart if something is in the same spot every day like a fake heron or owl statue they will figure out that it is not going to harm them.
- Install a scarecrow: No not the kind Dorothy runs into on the yellow brick road. The contech Scarecrow is a motion sensor device that connects to a garden hose and runs on a 9-volt battery. The scarecrow will cover 100sf of pond. It is important to make sure you test the battery regularly. You may want to replace it every month to be safe. This is my personal favorite. We have not had any fish loss in our ponds since installing our scarecrows eight years ago! I have been told that Otters are not deterred by this and if fact enjoy playing with the blast of water.
- Electric Fencing: Low voltage electric fencing works great to keep raccoons and other small critters out of the pond. It is not pretty but effective.
For those of you who are considering creating a pond or water garden have no fear there are ways to prevent fish loss and raccoon damage before you dig your pond. Sloping edges may look the most natural but it is also an invitation for small animals to enter your pond. When building a pond for Koi be sure the sides are straight and drop two feet or more. You can still have plant shelves installed on the pond edges with rocks on the edges to keep the Koi off the shelves and a steep drop from the shelves into the pond to keep the raccoons out.
photo credit: Madison Guy via photopin cc
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