Numerous big fish such as the Napolean wrasse, Red Sea (top left) and the Nassau grouper, Tropical West Atlantic Ocean (top right) are good
indicators of a healthy reef. The bright colours of reef species can warn others of the toxins in their skin (bottom left: variable neon slug, Molucca
Sea) or can camouflage them on the reef (bottom right: coral trout grouper, Red Sea).
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