The sex of a black moor goldfish is not identifiable until after it is one year old. During the breeding months from April to August, a male goldfish will sport white bumps, called breeding tubercles, on its gill coverings and pectoral fins. Additionally, females will appear to be much larger and fatter than males during these months.
The black moor goldfish is a good pick for beginning pet owners. It is a relatively hardy fish and can withstand colder temperatures than other members of the goldfish family. The average life span is 10 to 15 years, but it is not unheard of for a fish of this variety to live 20 years.
A black moor goldfish has a rounded body, slick metallic scales that give the fish its black color, and large eyes that protrude from its head. Young black moor goldfish are the color of bronze with relatively normal-looking eyes. As they grow older, they turn black and their eyes begin to push outward.
Black moor goldfish should not be kept in a tank with other highly competitive feeding fish. Because of the size and location of the eyes, the black moor is unable to see very well, which hinders its ability to compete for food.