Understanding the Coloration of Saltwater Fish

Have you ever walked through the aquarium at your local zoo and been mesmerized by the sight of hundreds, even thousands of colorful saltwater fish? Saltwater fish are some of the most brightly colored creatures in the world and they also exhibit some of the most unique patterns and color combinations. Think about the species of saltwater fish that you are familiar with and try to count the number of colors those fish display – it won’t be long before you run out of fingers to keep track of the different colors. If you have been involved in the aquarium hobby for any extended period of time you are probably familiar with the fact that saltwater fish are very colorful, but have you ever thought about why this is the case? Read more to find out why saltwater fish are able to display such bold colors and patterns while other members of the animal kingdom are not.

What do Fish See?

Camouflage is a common theme throughout the animal kingdom – many species have evolved to exhibit certain patterns or colorations which serve to hide them from predators. When you look at a tank full of saltwater fish, camouflage is probably the last thing on your mind. After all, how can a bright purple body covered in yellow and white spots be any sort of camouflage? What you have to realize is that fish see things differently than humans and, in some cases, the type of coloration just mentioned might be an effective disguise. Different species of saltwater fish see things in different ways – some species are nocturnal and have thus adapted to be able to see with limited light while others see things in terms of their surroundings.

Water is an incredibly effective filter of light so things look much different under one hundred feet of water than they do above the surface. It is also important to realize that the eyes of a fish perceive the spectrum of light in a different way than human eyes. Human eyes only contain three color receptors – receptors for blue, green and red – while some fish have four or more. Because that have additional color receptors, some saltwater fish have the ability to see ultraviolet light. If you think about it, saltwater fish are able to see more colors than the human eye so it makes sense that their bodies would have adapted to make use of this ability.

Colors as Camouflage

If you have ever had the pleasure of scuba diving in an underwater reef environment, you have firsthand knowledge of just how colorful reef systems are. In addition to the various colors exhibited by corals and other invertebrates, reefs are often teeming with hundreds or thousands of different species of fish, each with its own unique coloration. In such a colorful environment, brightly colored animals actually fit in rather than standing out. Think about it this way – if you were to toss a few colored scraps of fabric onto a multicolored quilt, could you step back and still be able to pick out the individual pieces of fabric? Rather than blending into their backgrounds through the use of neutral coloration, saltwater fish often employ a camouflage technique called disruptive coloration. The main idea behind this technique is that bold patterns made up of contrasting colors will actually make an object blend in when it is viewed in contrast with an equally variable background.

Not only are saltwater fish known for displaying a wide range of colors and patterns, but some even have the ability to change color. Species like the triggerfish and goatfish can change color at will almost as quickly as the chameleon. Other species may change color slowly throughout the day, adapting to the change in light and some go so far as to change sex as well as color. Bold patterns like stripes and spots on a fish may serve to confused predators. The butterfly fish, for example, has dark spots on its sides which may be mistaken for eyes. Bright colors can also be an indication of toxicity in certain species like the blue-ringed octopus. In short, there are many reasons why saltwater species display such a variety of bold colors and patterns – to understand it, you simply have to think in terms of their natural environment and what they must do to survive.