Roughhead blenny (Acanthemblemaria aspera) peering from a hole in a brain coral. This small fish inhabits coral reefs in the tropical western Atlantic Ocean, from Florida, USA, to northern South America. It spends much of its time hiding in holes and crevices in corals, emerging to feed on small planktonic crustaceans. It reaches a length of only four centimetres. Photographed off Bonaire Island in the Netherlands Antilles, in the Caribbean Sea.