Milkfish

The milkfish (Chanos chanos) is a widespread species of ray-finned fish found throughout the Indo-Pacific. It is the sole living species in the family Chanidae, and the only living member of the genus Chanos.

The repeating scientific name (tautonym) is from Greek khanos (χάνος 'mouth'). They are grouped in the order Gonorhynchiformes and are most closely related to the Ostariophysi—freshwater fishes such as carps, catfish, and loaches.

The species has many common names. The Hawaiian name for the fish is awa, and in Tahitian it is ava. It is called bangús (Tagalog: [bɐˈŋus]) in the Philippines, where it is popularly known as the national fish, although the National Commission for Culture and the Arts has stated that this is not the case as it has no basis in Philippine law. In the Nauruan language, it is referred to as ibiya. Milkfish is also called bandeng or bolu in Indonesia.

Habitat

Adults tend to school around coasts and islands with coral reefs. The young fry live at sea for two to three weeks and then migrate during the juvenile stage to mangrove swamps, estuaries, and sometimes lakes, and return to sea to mature sexually and reproduce. Juveniles prefer to settle in undisturbed coastal ecosystems that are semi-enclosed, calm, shallow, free from predators, and rich in aquatic vegetation. In their natural habitats, milkfish are very adaptable to both changes in environmental conditions and diet. Milkfish are good osmoregulators and extremely euryhaline.

The wide geographic distribution of milkfish has led to genetic variation in the species across the Indo-Pacific. Milkfish populations differ between the Hawaiian islands, the central Pacific islands, Tonga, Tahiti, Philippines-Taiwan-Indonesia, Thailand-Malaysia, India, and Africa. However, all populations are thought to be inter-breeding, thus they are all considered one species, and their genetic diversity is low. However, populations may still differ in their reproductive, migratory, and survival methods.

Distribution

Chanos chanos occurs in the Indian Ocean and across the Pacific Ocean, from South Africa to Hawaii and the Marquesas, from California to the Galapagos, north to Japan, south to Australia. A single specimen was reported in 2012 in the eastern Mediterranean Sea.

In 1877, the California Fish and Game Commission introduced one hundred milkfish from Hawaii to the inland waters of Solano County, California. The introduced population could not establish itself permanently and it is currently unknown how their presence affected the native ecosystem.

Milkfishes commonly live in tropical offshore marine waters around islands and along continental shelves, at depths of 1 to 30 m (3 ft 3 in to 98 ft 5 in). They also frequently enter estuaries and rivers.

Behaviour

Milkfish are omnivorous opportunistic feeders. Juvenile milkfish eat a variety of foods including phytoplankton, zooplankton, filamentous green algae, and small invertebrates. Similarly to juveniles, adults also eat benthic invertebrates and additionally planktonic and nektonic items such as clupeid juveniles.