Pacific Ocean: Why Are Reef Fish So Colorful?; The Oceans; Scientific American Presents; by Marshall; 4 Page(s)

Strangely enough, I became curious about the colors of fish not while diving in the crystal-clear waters of Australia's Great Barrier Reef, surrounded by countless incredibly colorful fish. On the contrary: I was in the murky, turbid waters of Heron Island's Coral Cay Lagoon, near the southeastern edge of the reef, close to Shark Bay.

Sitting slightly apprehensively at a depth of only two meters, I was trying to catch fish in a hand net. Suddenly I became dimly aware of hundreds of little black dots shooting past me almost at the limits of my vision in the silty water. Sucking air through my dive regulator and pondering this strange event, I was stunned to realize the black dots were the eyes of an enormous school of kyphosids swimming past on their way to the reef edge. The bodies of these fish, which are also known as drummers, are about 30 centimeters (nearly 12 inches) long and are a silvery-blue color. When vertical in water, they merged perfectly with the dim, blue light pervading the lagoon.