To care for a goldfish, house the fish in an appropriately sized tank filled with well-maintained and well-filtered water. Feed the pet a goldfish-formulated diet two to three times daily.
- Purchase an appropriately sized tank
Purchase a tank that holds at least 13 gallons of water and has a minimum dimension of four times the size of the adult length of the fish, two times the size of the width and three times the size of the height.
- Fill the tank, and install the filter
Set the tank in an area that is away from windows and direct sunlight. Fill the tank with water, and install an adjustable filter. Adjust the current to a level strong enough to stir the surface of the water but weak enough to allow the fish to swim easily. Install an aerator system if the filter does not stir the surface.
- Add plants, driftwood and other hideaway objects
Cover 50 percent of the aquarium with plants and hideaways.
- Test the water
Add a water conditioner. Test the water to ensure the ammonia, nitrite, nitrate, pH, KH and GH levels are fine. Ensure the water temperature remains between 68 and 76 degrees Fahrenheit.
- Feed a varied diet high in carbohydrates
Feed the fish two to three times daily with a diet of flakes and granules formulated for goldfish. Supplement live or frozen brine shrimp once in a while. Feed an amount equal to the size of the fish's eye.
- Clean the tank regularly
Siphon and refill 10 to 25 percent of the water in the tank weekly. Add water conditioner every time the water is replenished, and rinse the filter with tank water. Keep the gravel clean of debris.