Fish add color, movement, and life to any water garden. Even in a small container garden, you can put a small betta, which is one of the most tolerant of a wide variety of conditions.
Providing the Right Conditions
The type and number of fish that will thrive in your water feature depend on its design and your climate. Also keep in mind that fish need plenty of space, protection from extreme hot and cold, a method of cleaning or filtering out their waste, and food. For most fish, as rule of thumb, provide a minimum of 5 gallons of water for every “inch” of fish. So if you want two 3-inch goldfish in your pond, you’ll need a capacity of at least 30 gallons.
What Type of Fish?
Fish for your pond can cost just a dollar or two for small, common goldfish or hundreds of dollars for koi with rare or highly desirable markings. Fish for a water garden can be broken down into three main categories: Hardy goldfish, koi, and tropical fish.
Hardy Goldfish
The easiest fish for a water garden is the hardy common goldfish. They’re tough and can endure wider ranges of cold and heat. They’re also more disease-resistant than some other types of fish. Common goldfish also will tolerate poorer quality water conditions, such as lower oxygen levels. Other goldfish include comets and shubunkins. They are slightly less durable than the common goldfish, but still a good choice for beginning water gardeners. These hardy goldfish can endure water temperatures from just above freezing to 85° to 95° F, though not for very long. Less hardy goldfish cannot survive well in temperatures below 40° F. They include fantails, veiltails, block moors, and lionheads. In fall in cold climates, they need to be brought indoors to overwinter in aquariums.
Koi
Large and fantastically colored, these relatives of the carp can be trained to come to the edge of your pond and eat from your hand. Some koi can grow as large as 3 feet and need large ponds, accordingly. They do best in a pool that is at least 3 feet deep but prefer 5 feet. Koi do not tolerate warm water well and prefer temperatures of 39° F to 78° F.
Tropical Fish
In warm climates, or in cold climates where water gardeners are willing to go to some extra effort, tropical fish can be a lovely addition to your pool or pond. Most don’t like water temperatures below 70°, which means when air temperatures are dipping to below 50°F, it’s time to bring them indoors for more protection.
Introducing Fish
When you get your fish, acclimate them by first floating the plastic bag they come in in the pond for about 15 to 20 minutes to allow their body temperature to adjust to the new water. Never put fish into a pond that has been freshly filled. Instead, let the water sit for three or more days so that chlorine and other chemicals will dissipate. When you refill the pond, never fill it by more than about a quarter or the rapid changes in temperature and chemicals could shock your fish and kill them. Don’t feed new fish for 3 or 4 days.
Feeding
It’s easy to overfeed fish, which can pollute the water. Purchase a fish food made for your type of fish, and follow package directions exactly. As a rule, feed no more than an amount that the fish will gobble up in 5 minutes. In many outdoor water gardens, fish will nibble on water garden plants, mosquitoes, and other things. You may need to feed them only once or twice a week, or hardly at all. If they don’t show much interest in food when you do try to feed them, that’s a good indication that they’re getting plenty of nourishment naturally from their environment and don’t need additional food.
Overwintering Fish
In climates where temperatures get more than a little below freezing, you’ll need to provide winter care for your fish. Except for tropical fish, most fish will go all but dormant as water temperatures drop. They’ll move less to conserve energy and stop eating. They are good candidates for allowing to overwinter in a pond that has a deep zone that won’t freeze (up to 4 feet) and a pond set up so that there is always a patch of open water to allow for oxygen exchange. You can do this in warmer climates by keeping a fountain or waterfall running all winter, or by adding a floating electric heater over the winter.
In the northern third of the country, you’ll need a deep zone of 4 to 5 feet and run a small pond heater or substantial waterfall to keep the water open.
In the central third, you’ll need a deep zone of about 4 feet, but running your fountain or waterfall all winter long, in most cases, will keep the water open.
In the southern third of the U.S. and much of the Pacific Northwest, simply making sure your pond as a deep zone of at least three feet and having a fountain or waterfall run all winter long to keep any ice open is enough.
You can also bring fish indoors to keep in a plastic tub or glass tank over the winter, if you prefer, as long as the material is fish-safe and the water has a filter and aeration.
