The large fish staying still behind rocks is the giant grouper.
They live in southern Japan, Indian Ocean, and the Pacific Ocean. They can grow up to be 2 m in length and weigh 200 kg. There are records of giant groupers exceeding 3 m in length. It is the largest fish in Groupers.
They live in rocky areas and coral reefs of shallow waters. They are carnivorous and eat fish and shellfish. They even eat baby sea turtles and sharks at times. In Micronesia, people fear them as man-eaters.
They have spots all over their body. Their fin is yellowish with black spots, which gradually fade as they grow older.