Gary Bell/ Oceanwide / Whitemouth Moray (Gymnothorax meleagris) being cleaned by Cleaner Wrasse (Labroides sp) juvenile, Christmas Island, Australia

Shane Gross / Pelagic thresher shark (Alopias pelagicus) cleaned by a Bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) being cleaned by a bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

David Fleetham / Cleaner wrasse (Labroides dimidiatus) swimming alongside Golden damsel (Amblyglyphidodon aureus) looking for parasites, Fiji, Pacific Ocean.

Alex Mustard / Harlequin sweetlips (Plectorhinchus chaetodonoides) cleaned by a pair of bluestreak cleaner wrasse (Labroides dimidiatus). South Atoll, Tubbataha Atolls, Tubbataha Reefs Natural Park, Palawan, Philipp...

Alex Mustard / Bluestreak cleaner wrasse (Labroides dimidiatus) cleans among the sharp teeth of a predatory roving coral grouper (Plectropomus pessuliferus) beneath an overhang on a coral reef. Ras Mohammed National...

Tony Wu / Bluestreak cleaner wrasse (Labroides dimidiatus) cleaning Luna lionfish (Pterois lunulata). Shizuoka Prefecture, Honshu, Japan. June.

Gary Bell/ Oceanwide / Blue-streaked Cleaner Wrasse (Labroides dimidiatus) cleaning mouth and gills of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Whitemouth Moray (Gymnothorax meleagris) being cleaned by Cleaner Wrasse (Labroides sp) juvenile, Christmas Island, Australia

Gary Bell/ Oceanwide / Meyer's Butterflyfish (Chaetodon meyeri) being cleaned by Blue-streaked Cleaner Wrasse (Labroides dimidiatus), Great Barrier Reef, Queensland, Australia

Alex Mustard / Reef manta (Mobula alfredi) female swimming close to a coral reef, while cleaner wrasse (Labroides dimidiatus), tiny by comparison, pick parasites from her lips. Misool, Raja Ampat, West Papua, Indone...

Shane Gross / Pelagic thresher shark (Alopias pelagicus) cleaned by Bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.