How to Clean a Goldfish Tank. Your goldfish will need their tank cleaned regularly. Your tank cleaning schedule will depend on the size of your fish tank, the total number of pet fish, and your filtration setup. Remember to always wash your hands before and after cleaning a tank.
Minimum Tank Sizes for Goldfish. First Common Goldfish.Goldfish waste production overwhelms tanks sized for tropical fish. Some goldfish nip the fins of long-finned tropical species.

Our Guide to Goldfish Tanks. Goldfish are pretty much the most popular pet fish on the planet, especially with kids. Traditionally, goldfish were kept in round bowls, often without filtration. But is it cruel to keep a goldfish in a bowl? What kind of fish tank should a goldfish be kept in?

What size tank do goldfish need then? At least 120cm x 50cm x 50cm should be the very minimum for fancy varieties, while commons/singletails should not be housed in anything less than 200cm x 60cm x 60cm.

Tank size: For goldfish, a larger tank is generally better. A good starting point is a 55-gallon tank for a small number of goldfish. Grow bed size: The grow bed should be proportionate to the tank size to ensure adequate plant growth.
The recommended common goldfish tank size is at least 20 gallons per fish. Unlike some fancy varieties, the common goldfish is a slim-bodied goldfish that will take up less tank space in bulk but will grow longer than most fancy goldfish.