Taking Care of Goldfish in a Pond

Goldfish require about 20 gallons of water per fish. While a pond can never be too large, it can easily be too small if you have several very large goldfish. The fish should be able to easily swim in the pond without bumping into one another or into pond ornaments. Because goldfish are cold-water fish, they generally should be in a pond that is shaded. If you live in a very cool area, however, direct sunlight may help maintain pond temperatures. Goldfish do not need substrate, but substrate can add to the pond's appearance and provide a good location to plant pond plants. River rocks are ideal, and many pet stores sell them. Rinse the substrate with hot water before putting it in your tank, and avoid using substrate you found or that you purchased somewhere other than a pet store, as it may not be clean or suitable for fish.

A pond filter will ensure that your water remains clean and free of potentially dangerous bacteria. Filters are usually marketed according to tank size, so determine the size of your pond in gallons and choose a filter accordingly. You may need to regularly remove debris from the pond even if you have a capable filter.

Ponds tend to establish their own ecosystems over time, but for the first year or so you should drain 10 percent of the water and replace it every week. Add dechlorinator to any tap water you add to the pond, and regularly check the water's pH. Goldfish prefer pH levels to be slightly above 7, usually around 7.4.

Goldfish are cold-water fish that thrive at temperatures between 62 and 70 degrees Fahrenheit. In the hot summer months, you may need to provide a habitat for your fish indoors. Check the water temperature regularly and provide your fish with ample shade.

Goldfish hibernate when water temperatures drop, but if the pond freezes over, they can die from insufficient oxygen. Provide your fish with an air stone and feed them plenty of food in the months leading up to winter. This ensures they have sufficient fat stores to survive hibernation.

Goldfish are omnivorous scavengers that will eat a wide variety of foods. Brine shrimp, mosquito larvae and bloodworm are ideal sources of protein. Give your goldfish fruits such as chopped grapes and blueberries, and vegetables such as mustard and collard greens. While fish can subsist on fish flakes, they thrive on a varied diet.

Unless fish are very large, keeping them with other animals -- especially turtles -- is a risky proposition because they may be eaten. Goldfish also tend to require cooler temperatures than most tropical fish such as guppies. When introducing a new goldfish to the pond, carefully monitor the fish to ensure there is no fighting. Avoid introducing fish that are substantially smaller or larger than other fish in the pond.