Alex Mustard / Threadfin butterflyfish (Chaetodon auriga) feeding on ctenophore jellyfish. Sharm El Shiekh, Sinai, Egypt. Gulf of Aqaba, Red Sea.

David Fleetham / Diver swimming past coral reef with Gorgonian fans (Alcyonacea sp.), Red whip corals (Leptogorgia virgulata), Bluespot butterflyfish (Chaetodon plebeius), Fiji, Pacific Ocean.

Joel Sartore / Photo Ark / Auriga butterflyfish (Chaetodon auriga) portrait, Gulf Specimen Marine Laboratories. Captive, occurs in Indo-Pacific.

Joel Sartore / Photo Ark / Auriga butterflyfish (Chaetodon auriga) portrait, Gulf Specimen Marine Laboratories. Captive, occurs in Indo-Pacific.

Doug Perrine / Threadfin butterflyfish (Chaetodon auriga) portrait, showing darkened colour pattern during the day, normally displayed at night, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Threadfin butterflyfish (Chaetodon auriga) portrait, Kona, Hawaii, Pacific Ocean.

Doug Perrine / Schooling bannerfish / False moorish idol (Heniochus diphreutes) juvenile, cleaning a Threadfin butterflyfish (Chaetodon auriga), North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Threadfin butterflyfish (Chaetodon auriga) with Raccoon butterflyfish (Chaetodon lunula) in background, Kona, Hawaii, Pacific Ocean.

Doug Perrine / Threadfin butterflyfish (Chaetodon auriga) school swimming over reef, South Kona, Hawaii, Pacific Ocean.

Doug Perrine / Tiger shark (Galeocerdo cuvier) with remora or suckerfish clinging to flank, Bluefin trevally (Caranx melampygus), Racoon butterflyfish (Chaetodon lunula), Threadfin butterflyfish (Chaetodon auriga),...

Doug Perrine / Tiger shark (Galeocerdo cuvier) with fish hook in corner of its mouth, swimming across coral reef populated with Racoon butterflyfish (Chaetodon lunula), Threadfin butterflyfish (Chaetodon auriga), Su...

David Fleetham / Threadfin butterflyfish (Chaetodon auriga) portrait, Hawaii, Pacific Ocean.