Keep your fish safe from natural predators like cats. Pond fish tend to swim close to the surface to warm themselves in the sun. This makes them easy prey. Because cats can climb fences, even a fenced backyard pond is at risk. Homeowners often use trial and error to keep cats away. If you’re unsuccessful, the cost of replacing the fish is tiresome. There are methods that work effectively the first time.
Physical Deterrents - Retailers sell pond netting in different sizes (see Reference 1). Measure your pond using a tape measure. Add two feet to the dimensions to allow overhang. You want to cover the entire pond, plus have extra so a cat cannot simply lift an edge and reach the fish. Stake the edges of the netting into the ground. Prevent the cat from moving the netting with rocks or bricks.
Chicken wire is a suitable alternative to netting. If you have a small pond, spread a roll of chicken wire over the pond. Use rocks or bricks to secure it. Cats dislike the feel of chicken wire, so they'll stay away.
Pet-proof mesh screening is another way to protect your small pond. Home improvement stores sell the window and door screening in rolls. The vinyl-polyester fine mesh is seven times stronger than traditional screening (see Reference 3). Roll it over the pond and secure it with rocks or bricks. Cats cannot fit their paws through the mesh and cannot tear it with their claws.
A motion-activated sprinkler system is a worthwhile investment. These systems turn on when an animal moves within range of its sensors. Place the sprinkler near your pond. When a cat approaches, it's hit with a blast of water. After being soaked, a cat learns to stay away. Motion-activated sprinklers protect up to 1,300 square feet using no more than three cups of water. They run using one battery that lasts six months (see Reference 2).
Additional Ideas for Protecting Your Fish from Cats - Cats dislike certain odors. Rue is an herbal shrub that cats particularly dislike (see Reference 4). Plant rue around your fish pond to act as a natural deterrent. Cats also dislike black pepper and cayenne. Sprinkle them liberally on the ground near your pond where you see cats.
Try talking to the cat's owner. If the owner is not aware the cat is posing a problem, they cannot correct the behavior. Approach the pet's owner politely and discuss your concerns with the cost of replacement fish. If you use chemicals to control algae or mosquito larva, suggest these might pose a health issue if the cat drinks any pond water.
The depth of the pond helps provide fish with a safe area to hide. If your pond is a few feet deep, the fish will retreat to the bottom. Few cats will dip more than their paw into a pond. The cat will probably give up and leave your fish alone.
Fill your pond with plants that provide coverage. If a cat cannot see the fish, he's unlikely to stick around. Water lilies cover plenty of space and provide beautiful blooms in the summer. Your fish will hide under leaves when a cat is near.
When you're home, make your presence known. Spend time outside near your pond at various times of day. The more you're around, the less likely the chances that the neighborhood cat will enter your yard. If you see the cat, chase it off with a garden hose or sudden movements.