There's nothing more frustrating than hiding or skittish fish. Part of the joy of having a water garden is to sit by the pond's edge, feed your fish and relax while you watch them enjoy their underwater world. When they dash off and hide at the site of anything coming near them, or they hole up and never come out, it almost defeats the purpose of having koi or goldfish in your pond! Here are a few reasons why your fish may be hiding.
New to the Pond
It's tough to move into a new pond. If you've recently added new koi or goldfish to your water garden, you can expect them to be a bit shy or skittish. They need to check out their new home, get used to having new roommates and adjust to a new way of life. The fish already living in the pond could turn tail and hide, too. The new fish, depending on size, could spook the old fish, causing them to retreat to their favorite hole.
If this is the case in your pond, give the fish time to adjust. As soon as they're used to their new home and used to one another, they'll eventually come out of hiding. Encourage them to be social by tossing some floating food, like Staple Fish Food, into the pond. That'll bring them to the surface!
A word of advice: Before adding new fish to your pond, remember to quarantine them for a week or two in a separate tub to be sure they don't have any parasites or fungal infections that could infect the rest of your population.
Fish can also become skittish and hide after water changes. Any change to their environment - like the water quality, pH level, or oxygen level - can cause them to stress, and when they stress, they may retreat to their favorite hiding spots.
To keep the water quality as even as possible, test your water's pH, ammonia, nitrite, and phosphate levels regularly using a commercial water testing kit. You'll also want to keep your water well-aerated using a diffuser, like the Pond Aerator, to be sure the fish get an ample supply of oxygen. Also, be sure to check your filtration system regularly, cleaning or replacing filter media as needed.
Imagine looking up and seeing a clawed paw grab for you or a sharp beak slice through the water. Predators, like raccoons and herons, love a good sushi dinner - and that's how they see your fish! If your pond and its inhabitants have been visited by hungry predators, your fish are hiding for their lives.
To chase off unwanted visitors, you can try a range of deterrents, including the Great Blue Heron Decoy, GatorDefender, Heron Stop Reflector or a 3D-Coyote Decoy; pond netting, like the The Pond Guy PondShelter Cover Net; or reflective tape hanging from trees. Having 40-60% surface coverage of aquatic plants such as water lilies, water hyacinth or water lettuce will give your fish a place to shelter themselves from predators.
Under the Weather
Stressed or sick fish will also hide. If they're not feeling well, it's normal for them to segregate themselves away from the crowds. If you think your fish may be sick, try taking a closer look at it. Using a net, like the 3-in-1 Interchangeable Pond Tool, fish it out and put it in your quarantine tank. After you determine what the problem is, treat the fish and the pond accordingly.