If you have a pond, chances are it has happened to you. You wake up one morning, head out to feed the fish, and notice that a fish is missing. Or, if you are very unlucky, all the fish are missing! You look all around the edges, but they haven’t jumped out, nor are they hiding under the plants. Believe it or not, predators see your pond fish as a great snack, and you have just provided them with an expensive meal. Luckily there are many ways to keep your pond inhabitants safe from the most common uninvited dinner guests. The most common thieves are wading birds, especially great blue herons, raccoons, and neighborhood cats. Sometimes even humans have been known to make off with pond fish! The animals are all attracted to your pond for an easy meal, so you need to make it harder for them to get. The human is after the koi for either profit or for their own pond, but there isn’t much you can do to stop that.
Some predator control methods are very general, and will help keep your fish safer no matter what is eating them, while others are more specific to a particular pest. It is helpful to observe your pond and try to catch predators in the act, so you know what you are dealing with. If you cannot figure it out, consider installing an inexpensive scouting camera for a few days. These are motion triggered, and can give you photographic proof of who or what is stalking your pets.
A less common pond predator is the great blue heron. These magnificent wading birds can stand 5 feet tall, and can easily eat a pond fish over 12 inches long. They are active in the daytime, and are known to visit a pond over and over. When all the fish are gone, it is a pretty safe bet that you have a heron. They tend to eat all the fish, and then come back after you have restocked and do it again! Herons are legally protected migratory birds. You cannot legally capture, harm, or kill them, no matter how much you’d like to, so you have to focus on making your pond inhospitable to them. There are several methods to discourage herons.
More common is the crafty raccoon. Raccoons are active at night and are very smart. They tend to pick off fish one by one, and may leave remains at the water’s edge for you to find. They are excellent swimmers, but prefer to fish from dry land. Most raccoons will catch small to medium-sized fish. If a few fish are found half eaten in the morning, you probably have a raccoon family to thank. It is usually legal to capture raccoons in a live trap and relocate them. However, trapped raccoons are extremely aggressive and dangerous to handle. They can also carry several diseases that you can catch, including rabies. This is best left to the professional. In rural areas it may be legal to kill them with a hunting license, however non-lethal control is much better for everyone involved.
The most common predator in suburban ponds also tends to do the least damage. Stray cats are often attracted to ponds, but they dislike water, and are normally only mediocre fishers. They may catch a fish and leave it uneaten, or they may eat only part of it. If you find whole dead fish in the yard far from the pond, you may be after a cat. It is legal to trap and remove cats, but not legal to harm them in any way. Capturing a stray cat and taking it to a shelter is an excellent option, but remember mostly these are feral, wild cats. They will bite!
Now let’s examine some common control methods:
Deep water is effective for:
- Herons – These wading birds stand in the pond and scoop up fish, so if you can build all or most of your pond very deep, they will not have a place to stand and the fish will be able to hide safely in deep water
- Cats – Mostly dislike water, and will only go after fish near the surface
- A pond net is effective for:
- Herons – Again, if they cannot stand in the water, they will move on
- Some cats – They may be able to dislodge a net
Decoys are effective for:
- Most herons – They’re very territorial, and if they think another heron has already claimed your pond they will pass it by; this works great, unless they figure out it is plastic
Repellents are effective for:
- Most cats – They dislike the strong smell, and will avoid your pond if you spread repellent around the perimeter; this must be reapplied frequently
- Some raccoons – They’re sometimes repelled, but you can’t count on it
- The Scarecrow—a motion sensor that sprays a water jet at intruders—is effective for:
- Some herons – Some don’t seem to care, most fly away
- Most raccoons – They’re startled by the water and move on
- Cats – Really dislike being sprayed
- Most humans – Just in case, a face full of water is a great deterrent; just be sure you turn it off before your dinner party!
Now that you know methods to deter predators, choose the combination that works best for you. You’ll soon have your tranquil pond back, and your fish will be able to swim and live in comfort and safety.