Fish come in a stunning array of colors and patterns. From neon tetras to clown fish to angelfish, the diversity of colors is one of the things that makes fish so interesting. But why do fish have such colorful scales and designs? What purposes do the colors serve?
Camouflage
One major reason fish are certain colors is for camouflage. Blending in with their surroundings helps fish avoid being seen by predators. Species that live among coral reefs are often brilliant reds, oranges, and yellows to match the coral. Bottom-dwelling species tend to be countershaded, with dark colors on top and light colors on the bottom. This helps disguise them when viewed from above or below.
Fish like flounder change colors to match the sea floor as they swim from place to place. Other fish, like the wrasse family, can change colors over minutes or hours to adapt to changes in their environment. Being able to change color gives fish an important edge for survival.
Warning Colorization
While camouflage helps fish hide, color can also be used to make a bold statement. Warning colorization advertises that a fish is toxic or foul-tasting. The classic example is the clownfish. Its vivid orange and white stripes warn predators that it carries toxins.
Other fish use warning colors, too. Triggerfish have black bands and fins with neon blue, yellow, or orange spots. Lionfish and scorpionfish have bold stripes and splotches. The fouler the taste, the brighter the colors tend to be. Predators learn to avoid fish with these warning signs.
Communication
Fish also use colors to communicate with each other. During mating season, male fish often develop temporary, brilliant colors to attract females. At other times, fish use color to establish dominance and defend territories.
Specific colors can signal aggression or submission. For example, a red-bellied piranha turns a deeper red when it is asserting itself versus other fish. The ability to quickly change colors helps with communication.
Species Recognition
Schooling fish that swim together in large groups often have unique color patterns that help them recognize their own species. Damselfish, cardinalfish, and hamlets all have distinctive coloration making it easier to stay with their own kind in a mixed-species shoal.
Fish use coloring much like a uniform. It allows quick identification of fish from the same school. This helps maintain school structure and organization.
Environmental Influences
Sometimes a fish’s color is directly influenced by its diet or environment. For example, pink salmon get their color from eating krill and other small shellfish. Without the pigments from their prey, they would not turn pink.
The blenny is another fish that derives some of its color from its surroundings. Algae in blenny’s diet helps give it a greenish hue. The greener its diet, the more its scales take on a green tint.
| Fish | Color Purpose |
|---|---|
| Clownfish | Warning colorization |
| Triggerfish | Warning colorization |
| Flounder | Camouflage |
| Salmon | Dietary influence |
| Blenny | Dietary influence |
Cryptic Coloration
Cryptic coloration refers to patterns that help break up a fish’s outline. This makes the fish harder to detect. Examples include zebra stripes, dots, blotches, and mottled patterns in black, brown, gray, and green.
Species like stonefish and seahorses use their cryptic colors to hide in plain sight among plants and corals. Their complex color schemes act as visual camouflage.
Counterillumination
Some midwater fish utilize counterillumination to blend into the environment. Specialized cells called photophores produce light on the fish’s underside, disguising its silhouette when viewed from below.
Hatchetfish, lanternfish, and lightfish all use counterillumination. The light matches downwelling sunlight filtering through the water above, hiding the fish’s presence.
Thermoregulation
Certain fish colors may help with thermoregulation. Silvery fish that live in the open ocean have mirror-like scales that reflect sunlight. This helps camouflage them, but also keeps them from absorbing too much solar heat.
The reflective guanine crystals in their skin act like tiny mirrors to bounce light away. In cooler waters, fish may be darker to absorb more heat from the sun.
Buoyancy
Some scientists speculate that countershading may help with buoyancy control in open ocean fish. The dark upper surface may work like solar panels, warming and helping fish stay afloat.
At the same time, the light belly blends with sunny surface waters when viewed from below. So color may serve dual purposes for pelagic fish species.
Conclusion
As we have seen, fish come in a diverse array of colors, each with a special function. Colors help fish survive through camouflage, communication, warnings, and more. Color even aids species recognition and thermoregulation.
The variety of colors tell us fish have highly adapted and specialized uses for their striking pigments and patterns. After all, color can often be a matter of life or death in the fish world.