Red wag platy

What is the rule for what size tank to keep a common goldfish in?

Butterfly

Generally the recommendation is 20 gallons for the first goldfish and 10 gallons for each additional goldfish.
Carol

Red wag platy

So I could put two in a 29 gallon?

calinb

or 11 of 'em in my new 125 galllon? haha--this rule of thumb probably only works pretty well for medium size tanks. (Small tanks aren't good for goldfish at all, of course.)

Here's a calculator that's based on surface area:
http://www.bristol-aquarists.org.uk/...o/aquacalc.htm

24 - 30 square inches for each inch of fish is another rule of thumb. The above calculator is based on 24 sq. inches and indicates five fish would even be a bit over the limit for my 125, if each fish grows to 12 inches length.