Goldfish are very easy to keep and in most climates can live outside year round feeding on algae. Making a goldfish pond on a budget takes very little effort and can add interest to your garden or deck. A goldfish pond can be set inground as part of your landscaping, or a waterproof planting barrel can be turned into an attractive habitat, especially if you add plants.
The easiest method of setting up a little pond is to use a fibreglass whisky barrel, available at home and garden centres as planters. With the addition of some water lilies or irises, this is very attractive nestled in your garden or on a deck. Make sure you get the type of barrel that is watertight and doesn't have drainage holes at the bottom. Set it where you want it to be and fill it with water. You want to make sure it doesn't have a slow leak. Also the water should "age" for several days before you add fish.
The other way to make an attractive little goldfish pond is with a deep rubber container buried in the ground. Choose a large container. If the area you plan on placing it is in full sun, you may want to choose a clear or light colour because the water will get quite warm in a black container. Dig a hole big enough to bury it with a lip of about 7.5 cm (3 inches) above ground. Fill it with a little water to make sure it's level and use the dugout soil to pack it in until it is level and supported on all sides. Fill it with water and let it sit for several days. You can surround the lip with pavers or flagstones, or plant low-growing ground cover around it.
Any pet or aquarium shop will sell feeder goldfish, usually for pennies each. Since they are kept in crowded conditions, the fish are stressed, so expect to lose a few. Release them into your pond and keep your eye on it for a few days. With the addition of a few water plants, even little ponds become self-sustaining ecosystems and need little care. The goldfish will happily live off algae. You can feed them, but do so sparingly. If they are fed just a little every day, they will come to the surface when you approach as tame goldfish. Feeder goldfish can become quite large and live for many years. Once your little pond is established, you can add fancier goldfish, which are often not as robust but add interest to your goldfish pond.
If it gets below freezing during winter, you may need to bring your goldfish inside for winter. Goldfish can survive very cold winters but usually need a pond that is at least 90 cm (36 inches) deep so they can go dormant in the leaf mulch at the bottom. A barrel can be set on wheels and brought into the house for winter. One option is to set up a 90 litre (20 gallon) aquarium and transfer the goldfish to that when the temperature starts dropping towards the freezing mark. Keep the aquarium inside for the winter and when the weather warms up, transfer them back to their outside pond. The goldfish should survive the transfer in perfect health every year.
Some houseplants, notably Pothos, will grow very well if you just drop cuttings into the water. Plants help oxygenate the pond and keep the water clean.
Don't give any food to your goldfish if the water temperature is below 10 degrees C (50 degrees F). They won't eat it and doing this too often will foul the water from uneaten food.