Oyster Blenny

Found in pairs hiding in crevices, holes and dead, mussel and oyster shells (hence the name) or in tube worms holes over shallow estuaries and coastal reefs.
Western Pacific - Australia

Combtooth Blennies are the largest family of blennies, found in both tropical and subtropical waters and freshwater habitats, as the name suggests they have comb like teeth lining their jaws, well suited for scraping food off hard surfaces!
Reef and rock blennies are usually territorial and have their own areas of rock pools which they skip and jump over, scraping algae from the surface of dead corals. Some male Blennies have small harems of arguing females.
Males and females often have different colouring and features.