This Yellowtail Damselfish is showing its age. It has the bright yellow tail of an adult, but still has the bright blue spots of a baby.

Many fish change colors as they get older. Some scientists think these colors give clues about behavior. Adults often compete for food while tolerating the presence of juveniles. The special colors of juveniles tell the adult fish to give these youngsters a break. In some species, the juveniles are more aggressive while the adults are more mellow. The special colors of those adults are a signal for those fish to relax.

There are many different kinds of Damselfishes. Damselfishes are algae eaters, and often defend a small patch of algae growing on the reef. They will aggressively chase away other fish that try to eat their private gardens of algae. Some Damselfishes will kill corals to make a spot where algae will grow. If there are too many Damselfishes, then over time the reef might be destroyed. It takes predators like Nassau Groupers to keep the population of Damselfishes in check, keeping a healthy balance of fish and corals on the reef.

This Damselfish was swimming near the Sugar Wreck near Grand Bahama Island in water only 15 feet deep. Notice all the bright red and yellow coral and sponges growing on the steel beams of this shipwreck. There is a small Brain Coral on the wreck just behind this Damselfish's tail.

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