Blue-Green Chromis

Adults of this species can grow up to 10 centimetres (3.9 in) at maximum length. They have 12 dorsal rays, 9 to 11 soft dorsal rays, 2 anal spines, and 9 to 11 anal soft rays on their fins. It is a blue green fish. When they are breeding, males turn more yellowish.

The species is found in the Indo-Pacific, including the Red Sea. It is found in tropical and subtropical waters. In the Indian Ocean, they are found in the Red Sea, the Gulf of Aden, eastern Africa, Madagascar, Seychelles, the Persian Gulf, the Arabian Sea, the Maldives, Sri Lanka, the Andaman Sea, Australia, and Indonesia. In the Pacific Ocean, they are found in the Gulf of Thailand, Indonesia, the Philippines, China, Taiwan, Japan, the Great Barrier Reef, New Zealand, New Caledonia, Polynesia, Melanesia, and Hawaii in the Indo-Pacific part of the Pacific Ocean. In the eastern Pacific Ocean, they are found from the Gulf of California south to Peru and the Galapagos Islands. There are some reports of this species in the Mediterranean Sea. They live in coral reefs and lagoons. Individuals of this species are encountered in depths of 1 to 12 metres (3.3 to 39.4 ft).

Phytoplankton, zooplankton, and algae, copepods, and amphipods make up the diet of this fish in the wild. This fish also feeds on eggs that fail to hatch. It feeds by ram jawing.

Chromis viridis spawn over sand and rubble. The male prepares the nest which is shared with several females. The nest is located on sand or rubble. During spawning, the male turns more yellowish in color. The large number of eggs will hatch in 2–3 days. The male guards the nest and ventilates it with its fins and feeding on those eggs that do not hatch. Males feed on unhatched eggs to prevent them from being breeding grounds for microorganisms that can threaten the rest of the clutch.