This sailfish tang was being cleaned by two cleaner wrasses, which were getting rid of its parasites. I love when I can observe natural behaviour like this one. The cleaner wrasses have cleaner stations where they advertise their service. The bigger fish come and slow their swimming for the wrasse to perform its duties. Both parties benefit from the arrangement as the wrasse gets a meal and the bigger fish gets cleaned!
Nikon D700, Nikon 28-105 mm macro at 105mm, F8, 1/60th, ISO 400, Ikelite Housing and Ikelite DS160 strobe set on TTL.
Marsa Shagra South House Reef, about 20 metres down, Marsa Alam, Egypt.