EXPERT TOPIC MILK FISH
INTRODUCTION MILK FISH
EXPERT TOPIC The Milkfish (Chanos Chanos) is the national fish of the Philippines, referred to locally as the ibiya. They dwell primarily in the Indian Ocean, but are also present in the Pacific Ocean, from South Africa to Hawaii and the Marquesas, from California to the Galapagos, north to Japan and south to Australia. Milkfish commonly live in tropical offshore marine waters around islands and along continental shelves, at depths of between 1-30m. They also frequently enter estuaries and rivers. They are stenothermic fish, so therefore if you farm them in fish farms, they must be kept within extremely specific temperatures, otherwise they will fall ill and die. The milkfish can grow to 1.80m (5 ft 11in) but are often no more than one metre (39in) in length. They can reach a weight of approximately 14kg and can live up to an impressive 15 years. Milkfish have elongated bodies, with a generally symmetrical and streamlined appearance with one dorsal fin, falcate pectoral fins and a sizable forked caudal fin, which assists the milkfish in steering and swimming.
by Rebecca Sherratt, Production editor, International Aquafeed Their mouth is small and toothless, and their body a pale olive green, with silvery flanks and dark bordered fins. Considered to be iliophagous, (a fish that gains its nutrients from eating decomposing plant and animal parts), milkfish ingest the various micro- and meiofauna found on the ocean floor. They can also be weaned onto artificial feed, provided they are fed this within the first two-to-eight-days of hatching. Milkfish tend to school around coasts and islands amongst coral reefs. The young fry live at sea for two to four weeks before migrating during the juvenile stage, (also called fingerlings), to mangrove swamps, estuaries, and sometimes lakes. The reproductive cycle of the milkfish still remains relatively unknown. Their reproductive cycles have, however, been studied and are believed to be largely influenced by the lunar cycle and can often take place multiple times in a year, usually at night. Milkfish return to the sea to mature sexually and reproduce, when they reach between three and 15 years old. Females spawn at night between 0.5 and six million eggs in saline shallow waters, which take between 20 and 35 hours to hatch. Once born, the larvae are about 3.5mm in length, and rely solely on their yolk for nutrients for their first five days of existence.
32 | October 2018 - International Aquafeed