From longitude 40º E to about 100º W and from latitude 30-40º N to 30-40º S. Milkfish occur in the tropical and subtropical areas of the Indian and Pacific Oceans. The species has not been reported from either the Atlantic or Pacific coast of Central or South America.

HABITS:

Milkfish are herbivores and eat diatoms, blue-green algae, filamentous algae, and occasionally some animals, such as nematodes and copepods. They feed throughout the year either at the surface or on the bottom of ponds.

SPAWNING:

Maturation is reached rather late in life: at least age 4 years in males and 5 or older in females. Fertilization is external, the eggs being released in the open sea near shore to float to the surface. As many as seven million eggs have been estimated to be produced by a single large female. All attempts to obtain eggs from females either by natural spawning or by stripping in ponds have failed. Milkfish spawn at different times in various parts of their wide geographic distribution. In some waters they spawn twice in one year, late in the spring and during the fall; in others they spawn only during the summer.

GROWTH:

The growth of milkfish is easily adjusted by the amount of food provided to them, and by the stocking rates in ponds. They may reach as much as 1.8 lb after a year and 3.3-4.4 lb at the end of two. At about age 4, Chanos may reach a weight of 5.5-7.7 lb in ponds.

USES:

The farming of milkfish is an important industry in the Philippines, Indonesia, and Taiwan. The species is receiving considerable research attention at the Oceanic Institute in Honolulu, primarily on maturation and spawning of broodstock.

CULTURE:

This is an extremely important aquacultural species wherever it occurs. Sexual maturity is reached late in life and it is difficult to induce mature fish to spawn in captivity. Because large-scale artificial propagation has not been successful, seed fish are still obtained from natural reproduction. Larval rearing in outdoor ponds is successful. Records of pond-reared milkfish in Hawaii go back 300 years, when many ponds were located along the coast; today the few milkfish ponds still rely on wild-caught fish for stocking. In recent years the price and demand for milkfish have dropped.

REFERENCES:

Alava, V.R.; Kanazawa, A. 1996. Effect of dietary fatty acids on growth of milkfish Chanos chanos fry in brackish water. Aquaculture 144:363-369.

Ko, Wen-Ching. 1996. Effect of high pressure on gelation of meat paste and inactivation of actomyosin Ca-ATPase prepared from milkfish. Fisheries Science 62:101-104.

Kohno, H.; Ordonio-Aguilar, R.; Ohno, A.; Taki, Y. 1996. Morphological aspects of feeding and improvement in feeding ability in early stage larvae of the milkfish, Chanos chanos. Ichthyological Research 43:133-140.

Swanson, C. 1996. Early development of milkfish: Effects of salinity on embryonic and larval metabolism, yolk absorption and growth. Journal of Fish Biology 48:405-421.