Can guppys and goldfish be together in a tank?

Guppies and goldfish are two different species of fish that have different requirements. Guppies are tropical fish that need warm water, while goldfish are coldwater fish that need cool water. Guppies are also smaller than goldfish, and goldfish can be aggressive towards smaller fish. For these reasons, it is not a good idea to keep guppies and goldfish together in the same tank.