Goldfish Tank Size Selection

When it comes to selecting the appropriate tank size for your goldfish, there are several factors to consider - including the number of fish, and their size. Larger tanks are always better for the health and well-being of your goldfish.

The best rule is to choose a tank with at least 10 gallons of water for every goldfish, for 2 goldfish, you'll need a 20-gallon tank.

Goldfish can be kept in a bowl or a small 5- gallon (19 litre) tank. Some varieties of goldfish are much more active, so they need larger and preferably longer, tanks.

Common goldfish, comets, and shubunkin need big tanks. They need 40 gallons (151 litre) per fish.
Tank size depends on your goldfish species. 

Single-tail breeds need 40 gallons, and double-rail breeds 20 gallons each. A 10-20 gallon tank is the best size for a single goldfish.

Tank size selection table according to the type of Goldfish

Type of GoldfishMinimum Tank SizeAdditional Size for each extra Goldfish
Common goldfish 55 gallons Additional 20 gallons
Comet goldfish 55 gallons Add. 20 gallons
Shubunkin 55 gallons Add. 20 gallons
Fancy 20 gallons Add. 10 gallons
Ryukin 20 gallons Add. 10 gallons
Oranda 20 gallons Add. 10 gallons
Lionhead 20 gallons Add. 10 gallons

What is the maximum number of goldfish you can keep in a tank?

The maximum number of goldfish that can be kept in a tank depends on the size of the tank and the needs of the goldfish. In general, goldfish require more space than many other types of fish, as they produce a lot of waste and require good water quality to stay healthy.

What happens if the tank is too small?

If the tank is too small, it can lead to several problems and potentially harm the fish-

  • If the tank is too small, goldfish may become territorial and aggressive towards each other due to less space. This can lead to fighting and injuries, which can be fatal if left untreated.
  • Goldfish produce a lot of waste, and if the tank is too small, the waste can build up quickly, leading to poor water quality.
  • Goldfish can grow quite large, and if the tank is too small, they may not have enough room to grow to their full size. This can lead to stunted growth, which can cause health problems and a shorter lifespan.