Coral reefs
The warm, clear water of coral reefs. 58 fish on EveryFish so far.
Coral reefs grow in warm, clear, shallow tropical seas, built by colonies of tiny coral animals that lay down limestone. They cover a very small part of the sea floor but hold roughly a quarter of all marine fish species, often thousands in one region. The Coral Triangle of South-East Asia is the richest, and India's reefs lie around the Andaman and Nicobar Islands, Lakshadweep and in the Gulfs of Mannar and Kutch.
Crowded and colourful
Reef fish divide food and space finely. Grazers such as parrotfish and surgeonfish crop algae; butterflyfish pick at coral; groupers, snappers and reef sharks hunt along the edges; cleaner wrasses pick parasites off larger fish; and clownfish shelter among anemones. Most reef fish are territorial or stay close to one patch of reef, and many feed by day while others, such as cardinalfish and squirrelfish, come out at night.
Reefs under heat
Marine heatwaves cause corals to bleach and die, and the fish that depend on them decline. Mass bleaching has become more frequent, with the fourth global event confirmed in 2024. Overfishing, blast and cyanide fishing, pollution and coastal building add to the stress. Some reef fish carry ciguatera toxins, and a few, such as lionfish and stonefish, are venomous. Well-protected reserves often hold more and larger fish.
Famous coral reefs fish
Still to be written: Ocellaris clownfish, Green humphead parrotfish, Moorish idol, Bluestreak cleaner wrasse, Whitetip reef shark.
Further reading
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Photo credits on this page
The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.