Saddle anemonefish (Amphiprion ephippium) by its host anemone. This fish, also known as the red saddleback anemonefish, is found on the coral reefs of the eastern Indian Ocean. It lives in the stinging tentacles of a sea anemone, to which it is immune. This affords it protection against predators, which would be stung by the anemone. The fish picks parasites from its host anemone, thus forming a symbiotic (mutually beneficial) relationship with it. The saddle anemonefish can reach a length of nearly 15 centimetres. It is sometimes sold in the aquarium trade. Photographed in the Andaman Sea, Thailand.