Chromis viridis

Lore & Background

Chromis viridis is a blue-green fish that reaches a maximum length of 10 cm. It has 12 dorsal rays, 9 to 11 soft dorsal rays, 2 anal spines, and 9 to 11 anal soft rays. When breeding, males turn more yellowish in color. The species is sometimes called the 'blue-green chromis', though that name may also refer to Chromis caerulea, a close relative sometimes considered conspecific.

The species is found in tropical and subtropical waters across the Indo-Pacific, including the Red Sea, eastern Africa, Madagascar, the Persian Gulf, Australia, Indonesia, the Philippines, Japan, the Great Barrier Reef, Hawaii, and the eastern Pacific from the Gulf of California to Peru and the Galapagos Islands. There are some reports in the Mediterranean Sea. It inhabits coral reefs and lagoons at depths of 1 to 12 metres.

In the wild, Chromis viridis feeds on phytoplankton, zooplankton, algae, copepods, and amphipods, and also consumes eggs that fail to hatch, using a ram-jawing feeding method. It spawns over sand and rubble, with the male preparing a nest shared with several females. The male guards the nest, ventilates it with its fins, and feeds on unhatched eggs to prevent microbial threats. Eggs hatch in 2–3 days.

Reader's Guide

Chromis viridis is a widely distributed damselfish species, found across the Indo-Pacific and into the eastern Pacific, with some reports in the Mediterranean. Its significance lies in its common presence in coral reef and lagoon habitats, where it forms schools around Acropora coral heads. The species is also notable for its reproductive behavior: males turn yellowish during breeding, prepare nests on sand or rubble, and guard the eggs while consuming unhatched ones to protect the clutch. In the aquarium trade, the green chromis is relatively inexpensive and can be kept in small schools of odd numbers, with a minimum tank size of 110 litres for a school or 38 litres for a single specimen. Some aquarists have successfully bred it in home aquariums. It should not be housed with larger predatory fish such as groupers, lionfish, or eels, as it may become prey. The species' diet in the wild includes plankton, algae, and unhatched eggs, and it feeds by ram jawing. Its taxonomy includes a note of uncertainty: the common name 'blue-green chromis' may also refer to the close relative Chromis caerulea, which is sometimes considered conspecific.

Did You Know?

• Males turn more yellowish when breeding.
• The species feeds on unhatched eggs to prevent microbial threats to the clutch.
• It is sometimes called 'blue-green chromis', but that name may also refer to Chromis caerulea.

Gallery