Goldfish babies, or fry, change from black or dark-gray at birth to a golden color by age one. Environmental factors influence the degree of color they achieve.
A minimum of 12 hours of consistent exposure to natural or artificial light helps the fish fry to turn gold. Fry with insufficient light stay dark or turn gray or white. Genetic factors, such as darker parents, also impacts coloring. Dark coloring at birth helps these small fish escape pond predators, such as raccoons and birds. Goldfish are omnivorous scavengers and eat anything, although the overall health of a goldfish improves with the addition of live foods high in protein, such as bloodworms, brine shrimp and mosquito larvae.