No, "feeder goldfish" are actually comets and shubunkins, therefore they have the ability to grow up to 12-14" and therefore should live in ponds instead of tanks.
A fancy goldfish would live happily in a 29g tank, although they like to be in pairs.
It's not good to keep goldfish with other fish. Don't mix tropical fish with cold water fish, and if you're thinking of cold water white cloud minnows, the goldfish grow large and will eat them.
