David Fleetham / Hawaiian cleaner wrasse (Labroides phthirophagus) feeding on parasites on Crocodile needlefish (Tylosurus crocodilus) with coral reef below. Hawaii.

David Fleetham / Hawaiian cleaner wrasse (Labroides phthirophagus) cleaning Redlip parrotfish (Scarus rubroviolaceus) in coral reef. Kauai, Hawaii.

David Fleetham / Great barracuda (Sphyraena barracuda) with two endemic Hawaiian cleaner wrasse (Labroides phthirophagus) cleaning it. Hawaii.

David Fleetham / Eyestripe surgeonfish (Acanthurus dussumieri) laying on side with mouth open, a signal to attract Hawaiian cleaner wrasse (Labroides phthirophagus) Hawaii.

David Fleetham / Yellowfin goatfish (Mulloidichthys vanicolensis) with an endemic Hawaiian cleaner wrasse (Labroides phthirophagus) cleaning its mouth, Hawaii.

Alex Mustard / Crescent-tail bigeye (Priacanthus hamrur) portrait against blue water. Note there is cleaner wrasse in attendance (below mouth), Gubal Island, Egypt. Red Sea.

David Fleetham / Yellowfin goatfish (Mulloidichthys vanicolensis) and an endemic Hawaiian cleaner wrasse (Labroides phthirophagus) taking a close look in its mouth, Hawaii.

David Fleetham / Hawaiian cleaner wrasse (Labroides phthirophagus), an endemic to Hawaii, inspecting Orangespine unicornfish (Naso lituratus) for parasites, Hawaii.

David Fleetham / Hawaiian cleaner wrasse (Labroides phthirophagus), endemic, inspecting Long-jawed squirrelfish (Sargocentron spiniferum), Hawaii.

Doug Perrine / Indo-Pacific sergeant major fish (Abudefduf vaigiensis) being cleaned by Hawaiian cleaner wrasse (Labroides phthirophagus) in coral reef, Old Airport, Kailua-Kona, Hawaii, USA, Pacific Ocean.

David Fleetham / Ringtail surgeonfish (Acanthurus blochii) being examined by Hawaiian cleaner wrasse (Labroides phthirophagus), Hawaii, USA, Pacific Ocean.

David Fleetham / Orangeband surgeonfish (Acanthurus olivaceus) visiting cleaning station of Hawaiian cleaner wrasse (Labroides phthirophagus).They change colour to expose parasites, some turning black and others turni...

Doug Perrine / Reef manta ray (Mobula alfredi) with Saddle wrasses (Thalassoma duperrey) and Hawaiian cleaner wrasses (Labroides phthirophagus) at cleaning station on coral reef, Keahole Point, North Kona, Hawaii Is...

David Fleetham / Great barracuda (Sphyraena barracuda) swimming over seabed, being cleaned by Hawaiian cleaner wrasse (Labroides phthirophagus), Hawaii, Pacific Ocean.

Doug Perrine / Hawaiian cleaner wrasse (Labroides phthirophagus) cleaning a Raccoon butterflyfish (Chaetodon lunula), North Kona Coast, Hawaii Island, Pacific Ocean.

Doug Perrine / Two Raccoon butterflyfish (Chaetodon lunula) waiting to be cleaned of parasites by two approaching Hawaiian cleaner wrasses (Labroides phthirophagus), North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Ornate butterflyfish (Chaetodon ornatissimus) with Hawaiian cleaner wrasse (Labroides phthirophagus), Makako Bay, Kona, Hawaii, Pacific Ocean.

Doug Perrine / Hawaiian cleaner wrasse (Labroides phthirophagus) cleaning an Ornate butterflyfish (Chaetodon ornatissimus), North Kona Coast, Hawaii, Pacific Ocean.

Doug Perrine / Male Potter's angelfish (Centropyge potteri) being cleaned of parasites by Hawaiian cleaner wrasse (Labroides phthirophagus), North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Male Hawaiian saddle wrasse (Thalassoma duperrey), terminal phase, being cleaned by Hawaiian cleaner wrasse (Labroides phthirophagus), Makako Bay, North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Regal parrotfish (Scarus dubius) initial phase, posing vertically while being cleaned by a Hawaiian cleaner wrasse (Labroides phthirophagus), North Kona, Hawaii, Pacific Ocean.

Doug Perrine / Hawaiian Gregory damselfish (Plectroglyphidodon marginatus ) being cleaned by Hawaiian cleaner wrasse (Labroides phthirophagus), Pawai Bay, Hawaii, Pacific Ocean.

Doug Perrine / Whitetip reef shark (Triaenodon obesus), being cleaned by endemic Hawaiian cleaner wrasse, (Labroides phthirophagus) while resting in undersea cavern, Touch of Gray dive site, North Kona, Hawaii, Paci...

David Fleetham / Sleek unicornfish (Naso hexacanthus) at a cleaning station with a Hawaiian cleaner wrasse (Labroides phthirophagus), Molokini Islet, Maui, Hawaii, Pacific Ocean.

David Fleetham / Grey reef shark (Carcharhinus amblyrhynchos) with endemic Hawaiian cleaner wrasse (Labroides phthirophagus) in mouth, Pacific Ocean, Hawaii, USA.

David Fleetham / Great barracuda (Sphyraena barracuda) being cleaned by an endemic Hawaiian cleaner wrasse (Labroides phthirophagus) at a cleaning station, Hawaii.

David Fleetham / Yellowfin surgeonfish (Acanthurus xanthopterus) female at a cleaning station with endemic Hawaiian cleaner wrasse (Labroides phthirophagus) Hawaii.

David Fleetham / Sleek unicornfish (Naso hexacanthus) which has turned a darker than normal colour to help an endemic Hawaiian cleaner wrasse, (Labroides phthirophagus) spot parasites, Hawaii.