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Table of Contents
Bangus (Chanos chanos) is the national fish of the Philippines, called milkfish in English. Seen as an adaptable, tough, and sturdy fish, the bangus also swims in the Indian Ocean and across the Pacific, living in tropical offshore marine waters around islands and along continental shelves.
See the fact file below for more information on the Bangus or alternatively, you can download our 20-page Bangus worksheet pack to utilise within the classroom or home environment.
Key Facts & Information
- Milkfish possess a slender, compact, silvery body with a forked tail which is somewhat large and strong, thus letting them swim fast in the open sea.
- They have big eyes, a sharp snout with a terminal mouth, and cycloid scales.
- Their total body length varies from 50 cm to 180 cm, and their average weight ranges between four to 14 kg.
- A milkfish has 13 to 17 rays in their dorsal fin, six to eight anal rays, 15 to 17 pectoral rays, and 10 to 11 pelvic rays.
- Occasionally, there are cases of variant forms of milkfish.
- One strain, discovered in the Philippines and labelled as the ‘goldfish-type’, has unique long dorsal, pelvic, and anal fins, and a caudal fin as long as its body length. Another variant in Hawaii, Indonesia, and Australia, known as the ‘shad-type’, has a length-to-depth ratio of 2.0 to 2.5 instead of the normal 3.5 to 4.0.
GEOGRAPHICAL RANGE AND HABITAT
- Milkfish are endemic to regions in the Indian and Pacific Ocean, stretching from the east coast of Africa and Madagascar to the coasts of India and southeast Asia around Malaysia, Indonesia, New Guinea, Australia, north towards the southern tip of Japan, and east into the Pacific group of islands.
- They usually settle along the coasts of continents or islands, especially where reefs are well-formed. They also swim in large coastal lagoons. These fish can also be seen in clear, shallow, slime and warm tropical waters above 20°C, but rarely in areas that are affected by cold ocean currents.
- Adult milkfish also thrive in freshwater lakes in the Philippines, Indonesia, and Madagascar.
- Juveniles are spotted in large coastal lagoons, atolls, and freshwater lakes.
- Large groups of milkfish thrive in nearshore waters with well-formed coral reefs and in coastal lagoons, implying they are social fish species rather than solitary.
- Not much is recorded about how these fish communicate with each other during mating or how they interact in their natural habitat. Just like all fish, the milkfish has well-developed sensory organs, including a lateral line system and a great sense of vision.
- They are members of the Ostariophysi, thus they create and react to an alarm substance produced when their skin has been injured, mainly by their predator. This substance also serves as a warning for other fish to hide in order to avoid being eaten.
FOOD HABITS AND PREDATION
- Adults have a fully-developed epibranchial organ, which is a continuation of the alimentary canal. This organ also lets the fish eat plant matter.
- They prey on a number of food which depends on the kind of ecosystem. While larvae feed on zooplankton, juveniles eat benthic items, such as cyanobacteria, diatoms, detritus, green algae, and invertebrates like small crustaceans and worms. Adults, on the other hand, eat similar objects, and planktonic and nektonic prey, like clupeid juveniles.
- They are mostly open to attacks in the egg, larval, and fry stages. To lessen the effect of predation, milkfish generate large amounts of eggs in deep water.
- Their spherical fertilized eggs, which range from 1.1 to 1.25 mm in diameter, can be seen in the open sea of tropical waters. These eggs have a yellowish yolk and have missing oil globules. The outer embryonic membrane tends to be granular with a unique, segmented pattern. There is a narrow perivitelline space found in milkfish eggs.
- The embryo develops for about 20 to 25 hours in water temperatures of 26 to 32°C and salinity of 29 to 34 ppt.
- After hatching, the larvae reach 3.5 mm in length, having non-pigmented eyes and a shut mouth. In five days, the larvae rely exclusively on their yolk for nutrients.
- The larvae undergo a succession of complicated morphological, physiological, and behavioral stages, lasting about seven to 14 days, before turning into juveniles. Younger larvae, which can be seen near and far from shore, inhabit water depths of 20 to 30 m, while older larvae swim in the surface of the ocean. Other succeeding larval stages, which are about 10 to 17 mm in length, are commonly seen in nearshore regions.
- As soon as the milkfish are at least 20 mm in length, they are regarded as juveniles, which happen to have the same features and structure of adults. They reach brackish waters and coastal wetland ecosystems where there is enough food supply. The type of habitat, depth, and connection with the waters serve as factors in identifying the maximum size and length of stay of juvenile milkfish in the nursery grounds.
- Their growth and development is affected by water temperature, where the optimal temperature is between 23.7 and 33°C. A milkfish’s rate of development seems to be faster at higher temperatures, and those lower than lower than 20°C and up to 22.6°C can cause juveniles to look weak and inactive, making them an easy food for their predators.
- Milkfish breed near shore in tidy, open, saline, warm, and shallow waters over sand or coral reefs. These spawning areas are as close as 6 km offshore but should not exceed 30 km.
- They may spawn more than once annually, and primarily at night. Spawning is highly seasonal and may be affected by the moon cycle. Its length may be affected by surface water temperatures in some areas.
- Their breeding season is longer near the equator than those located at higher latitudes.
- Based on studies, parental involvement does not exist once the eggs are released in the water.
- The shortest documented lifespan of a bangus is three years, and the longest is 15 years.
This is a fantastic bundle which includes everything you need to know about the Bangus across 20 in-depth pages. These are ready-to-use Bangus worksheets that are perfect for teaching students about the Bangus (Chanos chanos) which is the national fish of the Philippines, called milkfish in English. Seen as an adaptable, tough, and sturdy fish, the bangus also swims in the Indian Ocean and across the Pacific, living in tropical offshore marine waters around islands and along continental shelves.
Complete List Of Included Worksheets
- Bangus Facts
- What About Bangus?
- Bangus Check
- Test Yourself
- Bangus All You Can
- Palengke Fish Finds
- Bangus Wiki
- The Country’s Fish
- Boneless Bangus 101
- Golden Bangus
- Economic Importance
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