Rainfordia opercularis, commonly known as the flathead perch, resides in coral reefs of the Great Barrier Reef and Coral Sea. Notable for its vibrant orange and blue stripes, this elusive species is often found hiding within crevices. It plays a vital role in the reef ecosystem as both predator and prey.

Rainfordia opercularis, commonly known as the Rainford's grunter, is native to the western Pacific Ocean. It is primarily found along the east coast of Australia, particularly in the Great Barrier Reef region and extending southwards to New South Wales. The species has also been recorded in the Coral Sea and around the Solomon Islands.

Rainfordia opercularis typically inhabits coral reef environments. It is commonly found in shallow waters, often at depths ranging from 1 to 25 meters. The species prefers reef flats and slopes where coral cover is abundant. The water in these regions is typically warm and clear, with temperatures ranging from 24°C to 28°C.

Rainford's grunter occupies an ecological niche as a small, reef-associated fish. It is known to hide in crevices and among coral branches, where it can avoid predators and find food. Its diet mainly consists of small invertebrates and plankton. The species’ coloration and body shape allow it to blend with the reef environment, providing camouflage from predators and aiding in its survival.