Gary Bell/ Oceanwide / Blue-streaked Cleaner Wrasse (Labroides dimidiatus) cleaning gills of Semicircle Angelfish (Pomacanthus semicirculatus), Great Barrier Reef, Australia

Shane Gross / Lemon shark (Negaprion brevirostris) adult resting and allowing a small cleaner wrasse feed off parasites. Grand Bahama Island, Bahamas.

Georgette Douwma / Blackspotted puffer (Arothron nigropuctatus) with a juvenile cleaner wrasse. North Sulawesi, Indonesia.

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.

Alex Mustard / Bluestreak cleaner wrasse (Labroides dimidiatus) attends to a Clark's anemonefish (Amphiprion clarkii) at a cleaning station on a coral reef. It is unusual to see an anemonefish at a cleaning stat...

David Fleetham / Manta ray (Manta alfredi) with cleaner wrasse, Manta Reef, Kandavu, Fiji.

David Fleetham / Manta ray (Manta alfredi) with cleaner wrasse, Manta Reef, Kandavu, Fiji.

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

David Fleetham / Map pufferfish (Arothron mappa) getting gills cleaned by Cleaner wrasse (Labroides dimidiatus), Philippines.

David Fleetham / Lined sweetlips (Plectorhinchus lineatus) with two cleaner wrasse (Labroides dimidiatus), Indonesia.