A while ago I had been strolling through the Aquarium, musing, when a stray thought crossed my mind: “the meaning of a fish is its color.” I had been involved in the Bay Area dance and theater scene prior to moving to Fresno for grad school and preoccupied with how juxtaposition of images in a painting, a film, or even a poem creates meaning, so it isn’t surprising that this thought percolated up through my brain.
It’s perfectly true for a biologist or fishkeeper that the color pattern of a fish can be a fish’s meaning. The color of a fish that matches the aesthetic the fishkeeper is trying to create with their piece of living art is meaningful, and that may be why the more colorful fish of the world are sought after by the aquarium trade.
For a biologist, the color pattern of a fish might be the one of the means to identify it. I often have to try to identify partially digested fish for my work as a master’s student, which can be complicated when fish have often lost primary identification marks through digestion. A fish’s color can fade in preservative as happens with some museum specimens.
The colors to fish are not intended to delight or inform human eyes, however, and the meaning of fish coloration is primarily the way it benefits the fish itself – what Ernst Mayr called the “Why” question of biology. As many people know, some animals use coloration as camouflage to blend in with their surroundings, either for protection or to ambush prey. In a case of convergent evolution, there are three distinct types of fish that not only have the coloration, but have actually altered their body shape to resemble plants (actually, plants and algae).
A widely shared example of cryptic coloration is countershading, where an animal’s coloration will be dark on top and fade to light below. This is to present coloration that matches the hue of the surface, for animals looking from below, or the bottom, for animals looking from above.
Some fish use coloration to warn predators away. One example of this phenomenon, aposematic coloration, is found in members of the lionfish family, especially the genus Pterois, which often have alternate red and white bands along with long, fanned out rays equipped with barbs.
A final example of color as meaning in the world of fish is the incredible variety of bright colorings displayed by tropical reef fish. According to this recent story on National Geographic’s website, (caution, registration required) at least some of the coloration, bright as it appears to us, actually can function as camouflage – it’s a matter of how the colors look to the fish, not to us.
From searching for the meaning of a stray thought about fish color to learning that fish might perceive colors in a different way from us, it has been a satisfying exploration of the meaning of color.