Have you ever noticed how fish color differs between species? Reef fishes are aware of their colors and they use this to their advantage in their surroundings by means of camouflage and protection against predators. At the same time, their colors can also be used for thermoregulation, communication between species or attraction of mating partners.
Various patterns such as horizontal and vertical stripes, unusual spots, “false-eye” patches and other shapes have evolved for decoration and concealment and play an important evolutionary role in their development. In addition, color patterns may also change during the development of certain fish mainly due to physiological changes during their lifecycle. An example is the Oriental Sweetlips (Plectorhinchus vittatus). During its juvenile phase it has an attractive brown-and-white and yellow mottled pattern whereas the adult can easily be recognized with its yellow and black horizontal stripes. Numerous other species of triggerfish, angelfish, parrotfish and wrasses also have these color morphs from juvenile to adult and it is assumed that these patterns or colors of the juveniles may be less visible to predators.
A number of reef fishes also have different colors according to whether they are male or female and in a community where sex change is the norm, this is an important manner of attracting a mate. Males tend to be more brightly colorful as is the case with many parrotfishes and wrasses and is very useful for attracting mates or to intimidate others. In the case of parrotfish, its been found that all females appear to change sex which is also accompanied by a change in color should they live long enough. Wrasses are also known for their drastic color changes accompanied by sex change.
Color patterns can also serve as a warning. Have you noticed how animals on land may all use the same tactic? Animals such as frogs, snakes or insects use vivid red, yellow or orange colors to signal that they are venomous, and predators would do well to stay clear of them. On the reef, plenty of fish use their striking patterns and bold colors as a warning. Examples of toxic or venomous fish include most pufferfish species with their distinguished bright colors and characteristic patterns or the venomous lionfish which are well known for their red, white or black bands with venomous spines and unique tentacles.
Attempts at understanding the unique range of colors of reef fishes and whether they have a biological significance have been long debated. There can be overlap amongst different functions and meanings of their color such as mimicry and color sexual trait. Their colorful appearance lies in the fact that fish see colors differently than humans and their position on the reef is likely affected by the absorption of light and the wavelength of colors. None the less, the debate about diverse fish colors and patterns and how they are changing remains a complex topic and requires much more research