How to Make a Goldfish Live for Decades

Believe it or not, a goldfish could live for 10-25 years or longer if it's given proper care. However, in standard conditions (usually a fish bowl) it usually lives for about 6 years. The Guinness Book of World Records cites a goldfish named Tish that lived 43 years after being won at a fair in England in 1956!^[1] Now you can help your scaly companion survive into the "golden years." It can be easy to forget that stress and hygiene can affect your tiny little fish enormously, but controlling those factors can have an enormous impact on your fish's lifespan. Little changes such as frequent water changes can help your fish live long past its expiration date.

Steps

1

Get the largest possible tank. Do not use a fish bowl; at least 75 liters (20 gallons) is necessary to make quality life for a single fish. Choose a tank with large surface area to increase the amount of oxygen in contact with the surface of the water (wider is better than taller).
2
Set up the tank prior to the purchase of a goldfish.
- Getting it ready may take four or more weeks. It is necessary to build up enough good bacteria to break down the fish' wastes. To do this, do a "fish-less cycle". Once completed, your goldfish aquarium will have more than enough bacteria to break down fish waste. Failure to cycle a tank will result in ammonia poisoning and death.
3
Provide mental and physical stimulation for the fish. Decorate the tank with rocks, driftwood, hardy live plants, etc. Be sure that any decorations you choose aren't hollow (harmful bacteria can grow inside) and that they don't have sharp edges (your fish might tear its fins). Provide your fish with different areas in the tank, such as an open area ideal for swimming and a hiding area.
- You can also train your fish various ways. If you feed them at the same time every day, they will soon be waiting for you at that time and grow used to your presence. Soon, you can teach them to eat from your hand. You can also use a fishnet with the netting taken out as a 'hoop' and train your fish to swim through it.
4

Add some equipment to increase oxygen diffusion into the water. A small air pump and air stone can be sufficient. You can also have the current from a 'waterfall' type filter help agitate the water's surface.
5
Clean the tank at least once every two weeks, but more frequently is preferable due to the large amount of waste goldfish produce. Consider buying a filter, because goldfish produce a lot of feces, which can lead to a buildup of ammonia and nitrites, which are potentially harmful to your fish. If you don't have a filter, clean the tank twice a week. This is essential. How often you do this will depend on the size of your tank, the number of fish, and the effectiveness of the filter. Real plants are great as they will help absorb some of the ammonia, nitrites and nitrates.
- Frequently test for ammonia and nitrite (you want both to measure zero). A pH test is also handy to ensure your goldfish's water is not too alkaline or acidic. This can be purchased at any pet store. Do not modify the fish's water, however, unless it is significantly different from neutral. Goldfish can tolerate a wide pH range, and pH modifying chemicals are not a lasting solution without more consistent monitoring than most people will do. A range of pH 6.5-8.25 is fine. Many municipal water supplies buffer their water up to around 7.5, and goldfish will live very happily in this range.
- Do not remove the goldfish during a water change. Using a gravel vacuum to suck debris out of the gravel can be done with the fish in the tank. Frequent partial water changes are much better than full (and stressful) water changes.
- If you do need to catch your fish, consider using a plastic container rather than a net, as the fish can injure its fins and scales while thrashing around. This also increases stress! If a net is the only option, soak it prior to use. Dry nets are much more likely to cause injury than wet ones. When using a plastic container, be careful and let the goldfish go in by itself, or it could be hurt.
6

Allow the water temperature to change as the seasons change. While goldfish don't like temperatures over 75°F (24°C), they do seem to like seasonal variations where the temperature falls to the high 50s or 60s (15-20°c) in the winter. Fancier goldfish are an exception and cannot easily tolerate temperatures below about 60°F (16°c). Be aware that goldfish will not eat below 50-55°F (10-14°c).
7

Feed the goldfish one to two times daily with food specifically designed for goldfish. If you choose to feed them more often, then reduce the size of the meals so you don't overfeed. Give them only as much as they can eat in a few minutes, and clean any leftovers immediately. If a floating food is used, soak it in water for a few seconds before feeding so that it will sink. This reduces the amount of air the fish swallows while eating, which in turn reduces the risk of buoyancy problems.