Harlequin sweetlips fish (Plectorhinchus chaetodonoides) with a cleaner wrasse (upper centre) inside a large sponge. Cleaner wrasse often make a specific object, such as a large sponge or coral outcrop, into their home. Larger fish then visit this "cleaning station" to have parasites picked from their skin. This is a symbiotic relationship: the visitors have harmful parasites removed and the wrasse get to eat them. Photographed in Borneo, Indonesia.
Model release not required. Property release not required.