The Skin of a Goldfish
Goldfish Skin and Slime Coat
Beneath a protective slime coat is the outer most layer of a goldfish called the epidermis. The slime coat layer is produced by the epidermis to help cut down surface tension for mobility in the water and it also acts as a protective barrier to fend off fungus, bacteria and parasites like Ich. The epidermis is a very thin delicate layer of living skin tissue that covers the scales. The outer layer of skin is so thin that extra precaution should be taken whenever a goldfish is handled; a dry net or hand can easily tear it.
The Colors of a Goldfish
Bellow the epidermis is the dermis. The dermis is layer of skin that contains cells that produce the color of a goldfish. There are two types of cells create color. The first are called chromatophores which produce ‘true’ color patterns from their pigment granules. They are named based on the color that is created by the pigment granules. Expansion and contraction of these pigment granules dictate what color the goldfish is. It’s common for goldfish to be one color and eventually transform into another color. Several factors that can lead to a color change in a goldfish include: water temperature, the age of the goldfish, the health or it’s diet.
The other type of cells in the dermis are called iridocytes. Iridocytes are cells that act like reflective mirrors and give the goldfish its metallic finish. Silvery guanine in the cells are responsible for their reflective nature. Unlike the chrmatophores, the silvery guanine in iridocytes do not expand and contract.
It’s the combination of theses cells that are responsible for every color and pattern a goldfish might display. These include the metallic, self colored goldfish with one solid color; a metallic variegated color of two or more colors; and calico colors that are created by three different scale patterns. The three types include: the metallic scales that has guanine present; nacreous scales that contain some guanine; and the matt scale type that has no guanine present in the dermis.
Goldfish Scales
A goldfish’s scales are created in the dermis and are bony plates that over lap like the shingles on a roof. As a goldfish grows, its scales grow with it. When the water is warm in the summer months the goldfish grows fast and when the water is cold in the winter months, the goldfish grows slowly. Under microscope, goldfish scales of a mature goldfish will have several growth rings. In the summer they grow spread out and in the winter they grow tightly close together. By counting the spread out and tightly compacted groups of rings, one can get the age of a goldfish. If a scale is lost do to an illness or injury, it will quickly grow back much like how a finger nail grows back but it will lack these rings.
photo credits: Andrew
