Milkfish CultureIntroduction: The milk fish is one of the most important food fish and protein source in the world. It makes up about 40% of the Philippine‛s total aquaculture production. Milkfish culture is carried out mainly in brackish water ponds. production methodsintensified and supplemental is increasingly use to supply the increasing demand.
• People of Indonesia, Philippines and Taiwan use several hundred thousand of hectares of lands to grow Milkfish.• This large growing activities use large numbers of young milkfish fingerlings.• In the past, these large number of fingerlings were met by captured wild fingerlings.• After the wild fingerlings were depleted in many areas in the past 20years, large milk fish male and females.• Maintain in ponds or net cages have been used to reproduce the highly needed finger lings.
Common name of Milkfish in many countries:• USA: Milkfish• Japan : Sabahii• Central taiwan : masaba• south taiwan : Hi Tsu Hii• China: Su Mu Yii• Philippines : Sabalo,Bangus• Hawaii : Pua Awa,Awa• Indonesia : Bendeng Bolu
Habits of Milkfish:• Milkfish are herbivores and eat diatoms, blue, green, algae, and occasionally some animals such as nematodes and copepods. they feed throughout the year either at the surface or on the both pond.
Habitat of Milkfish• Young milkfish migrate from the seas to the coastal areas and may arc end estuaries, rivers and lake before migrating back to the sea at maturity benthopelagic , catadromous, fresh H2o.depth range 10-13m.
Biology of Milkfish:• Adults occur in small to large schools near the coastal or around islands where reefs are well developed.• Eggs and larvae are pelagic up to 2-3 weeks. older larvae migrate on shore and settle in coastal wetlands during the juvenile stage or occasionally enter fresh water lakes.• Juvenile and sub adults return to sea where they mature sexually. spawns only in fully saline water. larvae eat zooplankton. juveniles and adults cyanobacteria, soft algae, small benthic invertebrates and even pelagic fish eggs and larvae.• Larvae are collected from rivers and are grown in culture ponds into juveniles which are marketed fish.
Spawning of Milkfish• Maturation is reached rather week season, april-july and september-november. Late in life at least age 4 years in males and 5 or older in females.• Fertilization in external, the eggs reign released in the open sea near the shore do float to the surface.• As many as 7million eggs have been estimated to produce by a single large female.• All attempts to obtain from females either by natural spawning or by stripping in ponds have failed.• In others milkfish spawn only during summer.
Early development stage of young milkfish:• Blastula stage• Eye-cup forming• Pigmentation forming• Body elongation• Lath embryo• Hatching• Stage 1:yolk sac larvae(3.2-5.4 mm) 3 days• Stage 2:pre flexion larvae(5.0-6.3mm)5 days• Stage 3:flexion larvae(5.4-10.0mm)6 days• Stage 4:post flexion/fry(6.4-14.9mm)7 days• Stage 5:transformation(6.4-14.9mm)2-4 weeks
Culture of milkfish• This is extremely important aqua cultural species wherever it occurs. sexual maturity in reach late in life and it in difficult to induce mature fish to spawn in captivity. because large scale artificial propagation has not been successful, seed fish are still obtained fro natural reproduction.• Larval rearing in out color ponds is successful.• 1.pre culture- benthic algae 10-30 ppt.• 2.pond culture(brackish water) plankton method• Cage culture(mariculture)
Site selection for Milkfish Culture:• Naturally or inexpensively, qualify for locating milkfish culture.• Ponds should provide water retentive soil base, exposed by digging of top soil of the site to pond bottom and embankments.• The soil should possess basic mineral nutrients and respond readily to organic and inorganic fertilizer.• There should be a dependable source of perennially available water in adequate quantity for the size of the culture.
.Self draining ponds should be use on sloping sites..The physical and chemical properties of the water arewithin acceptable limits, such the water quality can befurther manipulated by chemical treatment to suitaquaculture needs..the site is easily accessible by rail and/or road and air..there is a market in the vicinity..there is no industrial, domestic or pesticide pollution atthe site..there are reasonable educational and medical facilitiesavailable in the vicinity of the site.
Pond preparation:• Pre-stoking Management• Cleaning:• At first we must clean the pond properly.• We have to clean aquatic weed and cut down large plants so that the sunlight directly fall into the pond.• Maintenance of sanitation and good water quality are the two most important task in the hatchery.• For hatcheries in good sites with biologically clean water, tanks are simply cleaned with detergent solution and Clorox, or sprayed with hot water and diluted Clorox applied to sites (Mc Veyand fox 1983), then dried for at least a day before stocking.
• After each run, tanks as well as pipelines and materials use in the hatchery are disinfected with 12%Na hypo chlorite at 200 ppm for 24 hrs.
Ploughing the pond:• The ponds are drained completely during low tides. the bottom is leveled, rake with a wooden rake or ploughed to bring the sub- surface soil nutrients to the surface and to eradicate weeds.• The pond bottom is leveled in such a way that it slopes gradually towards the deepest portion of the pond.
Drying ponds:• The ponds dried and exposed to the sun for two or three days until the layer of surface soil cracks.• In order to get rid of any predatory fish or predatory pests burrowing in the mud.• Drying also helps in the mineralization of organic mailer in the soil.
Fertilizing:• The pond is then treated with chicken manure at the rate of 2 tons/ha.• Water is just to cover the pond bottom and 150kg/ha of 16-20-ONPK fertilizer or half that quantity of 18-46- ONPK fertilizer per ha, is added after 2or 3 days.in order to speed up the breakdown of the chicken manure, urea may be added at the rate of 25kg/ha. Within a week lablab growth start.• The water level in the pond is then gradually increased to 25-30 cm in a period of one and half-month increasing the level by 3-5cm each time.
Watering:• Watering should be done after 4-7 days of fertilizing. Watering is done by water pump or other source. Water is done up to 2-4 feet.
Stocking:• Fry can be stocked directly in the nursery pond if the salinity of the water in which the transported is approximately the same as the salinity of the pond water.
Stocking management:• The density of fry in the nurseries is generally 30- 50 per m². some exchange of water may be needed it is reported that the growth of Milkfish fry is retarded at salinity above 45ppt.• Favorable temperatures for growth are above 23˚c. artificial feeds like rice bream or dried cumut are provide.• In about one and half to two, the fry have growth to a weight of 1-3g and are then either stock in the rearing ponds or transferred to transition or stunting ponds.
Fry selection• Fry should be healthy• Fry must be diseases free• It can tolerant environmental fluctuation• The fry captured are between 10-30mm. In length.
Fry collection and transportation:• This includes fry barriers or fences, sine net and bulldozer nets.• The collected milkfish fry placed in well ventilated containers preferably wooden vats of big earthen jar filled with clean brackish water.• The containers must be kept in cool areas.• Over exposed to sun light should be avoided.• The fry should also be brought to the concessionaries buying stations without delay.
Stocking density:• Repeated stocking is done with fingerlings and fry of different sizes.• Stocking rates may be as follows:2000 to 2500 fish per ha. For large over wintered fingerlings:1500to200 fish per ha. For small:6000 to 7000 fish/ha.• Some ponds are stocked at a low density for 4000 fry/ha. To ensure faster growth.
Species composition:• In freshwater ponds milk fish can be cultured with mullet, tilapia and carp with yields averaging 7,500 kg/ha.• In brackish water ponds, shrimp, mud crabs and sea bass most common species combined with milkfish.
Feeding of Milkfish:• Fish feeds are 2 types, such as natural feeds – plankton, benthos which is produced in ponds by minoring.• The other is supplementary feed such as rich bran, wheat brand, sesame oil cake, mustard oil cake, grasses etc.
Monitoring:• Environmental parameters such as water temperature, salinity and pн should be checked twice daily.• MAINTAINING WATER QUALITY:• Cleanliness must be strictly maintained to ensure best results. constant vigilance is required to prevent or control out breaks of disease.• The wall of the tank should be cleaned with a soft brush every third day.
Health management of milkfish:• 1:regularly have to control the water quality.• 2:regularly have to given the supplementary feed and life food.• 3:have to observe the growth rate of milkfish.• 4:have to maintain the pн temp. salinity etc.• 5:regularly have to observe the fry to free from discuses and parasites.
Suitability of culture of Milkfish:• Economically friendly• Highly productivity• High community acceptance• Sustainable culture of Milkfish depends on various factors,• For sustainable development the following variables are important.• Production aspects• Environmental aspects• Economics and community aspects
Advantages of Milkfish culture:• Milkfish spawners have a high fecundity, they are capable of producing an abundant supply of fry.• The fry are easy identify and are caught in season.• Milkfish are hardy, euryhaline and are capable of enduring a salinity range of 0 to 158 ppt.• They are basically herbivorous but they can be also omnivorous.• Formulated feed for Milkfish can be available at low costs.
Advantages of milkfish culture:• 1.Milkfish spawners have high fecundity.• 2.the fry are easy identified and are caught in season.• 3.Milkfish fry can be obtained in captivity and they are not difficult to rear.• 4.Milkfish are hardy, capable of enduring a salinity range of 0 to 158ppt.• 5.are basically herbivorous but they can be also a omnivorous• 6.formuated feed• 7.highly potable
Disadvantages of Milkfish culture:• 1.low survival rates for larvae.• 2.over wintering-sometimes high mortality occurs due to low temp.• 3.diseas-as a result of high density.• 4.coordination of population and marketing.• 5.high production cost• 6.occurrence of calamities• 7.security problems• 8.inflation• 9.shortage at fry supply• 10.lack of infrastructure in many areas• 11.environmental problems