The goldfish is closely related to the carp, and like the carp was introduced to this country from overseas. While there are orange individuals in the Hudson, these tend to be easy pickings for predators; one study of the diet of ospreys along the Hudson found that goldfish were a common prey of this fish-eating hawk. Thus the goldfish we catch are more likely to be olive green or brown than orange or gold. Goldfish prefer fresh water, and may grow up to eighteen inches long.