Passage Summary: Scientists used to think bright fish were hiding in bright reefs, but it turns out the reefs aren't actually bright, so the camouflage theory doesn't hold up.

Conclusion: The theory that the bright colors of reef fish serve as camouflage against colorful coral reefs is incorrect.

Reasoning: When the fish are removed, the reefs themselves are actually quite dull and monochromatic, consisting mostly of browns and greens.

Analysis: To identify the conclusion, focus on the author's reaction to the 'suggestion' mentioned in the second sentence. The word 'however' marks the transition to the author’s main point: that the camouflage hypothesis is 'mistaken.' The final two sentences serve as evidence, proving that the reefs lack the color variety necessary to provide camouflage for brilliant fish.