Goldfish Classification - Scales

The body of a goldfish is covered with overlapping scales. The scales are composed of a hard, bony substance. They serve to protect the fish, reducing the chance of injuries or infection.

These are covered by epidermal tissue. Numerous glands secrete mucus and produce the slimy effect we view as slippery. The slimy coating helps the fish to swim more easily in the water, reducing the friction between its body and the water itself. The slimy coating also acts to guard against injury or infection.

The scale is actually transparent; the color of the goldfish usually comes from the dermis, the lower or inner layer of skin. The forward end of each scale is attached to the dermis. The scales overlap each other like shingles on a house, providing a solid wall of protection as well as comfortable movement "The wild form of the goldfish/ according to Neil Teitler, a goldfish expert, "has between 28 and 31 scales along the lateral line and 6 scales between the dorsal spine and the lateral line." The lateral line is a series of indentations having to do with the senses and will be discussed later.

For every variety of goldfish, the specific number of scales remains the same within that group, from fish to fish. For each season of growth in a goldfish (approximately one year, provided that there is a six- to eight-week drop in temperature), the goldfish develops a ring in its scales. The number of rings on the scale determines the age of the fish. These rings are called circuit.

Scale Types

Goldfish can be characterized based on four different kinds of scale groups: metallic, matt, nacreous and calico.

Metallic fish exhibit a shiny, scaly exterior, such as is seen in the Comet. These scales contain a crystalline substance called guanine. Guanine is responsible for the sheen of the scales. The more guanine, the shinier the scale.

Some scales lack guanine almost entirely. They are called matt scales and exhibit no reflective tissue anywhere on the fish's body; rather, they have a flat or skin like look to them. Truly matt-type goldfish are often not available commercially. They lack intensive coloration and do not seem as hardy as other fish. Matt fish are sometimes referred to as scale less. This is incorrect—there is no such thing as a scale less goldfish.

When metallic- and matt-type scales are both found on a goldfish it is known as nacreous. Some individual scales, or whole sections of the body, might feature a metallic-type finish, while others might feature a matt-type finish.

Many feel that calico is really a part of the nacreous group. This category has gained popularity, as it classifies any goldfish with three or more colors appearing anywhere on the body.