MILKFISH

Introduction

Milkfish, Chanos chanos (Forsskal), locally known as "bangus" or "bangos", is the predominant species being cultured in the Philippines. Hundreds of years ago bangus was grown in ponds along coastal areas. That was the beginning of fish fanning. Bangus is a popular table fare among Filipinos. To the biologist, it is an innately sturdy fish, being able to adapt and thrive even in the confined, unnatural environment of the fishpond. This characteristic is not often found in most other fish species.

Milkfish production represents one of the main sectors of the nation's fishery industry .Fish culture is distinct from the marine and inland capture fisheries in that its research and development is like that of animal husbandry which requires a different approach. Aquaculture is concerned with such inputs as seeds, land, water, fertilizers, chemicals and feeds. Its research involves the determination of the physiological requirements of the culture species and the development of culture methods from laboratory to commercial scale. Aquaculture development requires government assistance in providing credit, extension and training and other incentives.

Milkfish is a traditional culture species, and has been studied for a long time. But there is still much to be studied about this fish and its culture to understand and gain greater control of factors that favor its growth and production.

Milkfish is the only species in the Family Chanidae and is most closely related to carps and catfishes. Milkfish lives in the warm waters along the continental shelves and around islands in the Indo-Pacific.

Site Selection

Select existing brackish water fish farms that are fully developed and operational. Former prawn farms can be used for milkfish farming. The site should have: high tidal range and can hold water at least one meter deep; good water quality and more or less have constant salinity and temperature throughout the year; longer dry season, sandy clay loam, silty clay loam; and access to roads and power supply.

Pond Layout

1. Improve or modify existing structures to suit the management requirements of the proposed production scheme.
2. Concentrate on the repair and strengthening of dikes, cut-and-fill leveling of pond bottom, and construction of diagonal canal, drain canal and drain culvert gate to improve pond structures.
3. Modify pond structures to improve water management and stock manipulation systems as well as to meet desired management schedules and production targets. The pond can be of any size (the bigger, the better) for optimum production using the modular method.
4. Divide pond into four compartments: nursery pond (NP); transition pond (TP); formation pond (FP); and rearing pond (RP).
5. Provide a separate culvert-type drain gate and canal system opposite the inlet gate and canal system for rearing ponds to effect efficient water exchange and circulation.
6. Construct an inside-pond diagonal canal to facilitate draining and harvesting of stock.

Pond Preparation and Food Requirement

1. Carry out thorough pond preparation such as crack drying, liming and tilling once a year.
2. Prepare the ponds grown with lab-lab before fish stocking.
3. Apply organic and inorganic fertilizer to stimulate growth of natural food organisms.
4. Extend pond preparation and food growing in grow-out ponds to 45 days to allow more time for the abundant growth of lab-lab

Figure 2. Schedule of pond preparation and food growing

Cumulative days for completion of activities / Activities:

• 1 Pond draining, soil sealing, leveling and repair
• 2-7 Pond drying
• 2 Gate screening
• 2 Pest predator control
• 2 Liming (optional for low pH)
• 7 Washing
• 8 Organic fertilization (2 tons/ha)
• 8 First water intake, 5 cm
• 8-17 Evaporation
• 11 Inorganic fertilization 3 sacks/ha 21-0-0
• 18 Second water intake, 10 cm
• 18 Fertilizer dressing, 25 kg/ha 16-20-0
• 25 Third water intake, 15 cm
• 25 Fertilizer dressing, 25 kg/ha 46-0-0
• 32 Fourth water intake, 20 cm.
• 36 Fertilizer dressing, 25 kg/ha 16-20-0
• 39 Sixth water intake, 25 cm
• 39 Fertilizer dressing, 25 kg/ha 16-20-0
• 45 Sixth water intake, 30 cm
• 46 Fish stock

Pond Water Management

1. Increase water depth from 0.6 m to 1 m particularly during the last two months of culture operation. Note: An abrubt increase in water depth will cause lab-lab to detach and float. Install fine-meshed screens (bastidor or lumpot) at the gates to prevent the re-entry of wild species or the possible escape of stock.
2. Monitor water quality parameters (turbidity, salinity, dissolved oxygen, temperature regularly to check for any sign of risk. Maintain the optimum water condition to support maximum growth of milkfish.
3. Change water at least every two weeks or as frequent as possible.
4. Install a stand-by water pump to maintain desired water depth when water management through tidal fluctuation is not possible.

Do’s and Dont’s in setting up and managing a fish pond.

Harvesting

Harvesting milkfish that have attained the marketable size can be done either through the current method locally called as pasubang or the total draining method. Total draining is the common method for harvesting milkfish. However, this lowers the quality of the fish because mud sticks to the fish.

To maintain fish quality, the pasubang method can be used. This takes advantage of the tendency of the fish to swim against the current. The method is carried out by draining water in the pond particularly during low tide to induce fish to swim through the gate.

Close the gate when all the fish have been impounded. Total harvest is done manually by collecting or picking the remaining fish from the pond bottom.

Packing for transport

Part of the business is transporting the goods to the market. To ensure that fish will remain fresh until they reach their destination, they must be packed with sufficient quantity of ice and loaded with care.

Methods of packing fresh fish for transport

1. Wash the fish with pond water prior to icing and sort according to size.
2. Pre-chill or immerse the fish in a chilling tank, box or banyera with ice water immediately after harvest.
3. Dip the fish in ice water before packing to keep them from losing scales due to subsequent handling.
4. Spread a layer of crushed ice 15 cm thick at the bottom of the transport box. Make sure the ice is compact to minimize thawing and to cushion the fish.
5. Lay about 100 kg of the fish on top of the crushed ice. Arrange the fish heads pointing to the one direction only.
6. Spread another layer of crushed ice 5 cm thick on top of the fish.
7. Repeat steps 2 and 3 until the last layer of fish is 15 cm below the top of the box.
8. Place the last layer of crushed ice 15 cm thick on top of the last layer of fish. The bottom and the top layers of ice should always be 15 cm thick.

Note: If the fish will be transported by land, a 1:2 ratio of ice to fish (weight basis) is needed for 1 1/2 hours of travel, and a 1:1 ratio for 3 hours of travel. However, if transporting by boat or ship, do not remove fish from the styrofoam boxes. The fish can stay fresh in a styrofoam box for 12 hours.

Advantages of pre-chilling

Pre-chilling the fish will prevent excessive damage and will keep the fish looking fresh. It also removes blood, slime, dirt and bacteria from the skin of the fish, and slows down enzymatic activities, thus minimizing further deterioration.

Ecological considerations

If not properly planned or managed, fishponds may adversely affect the environment, e.g. by causing water pollution. To mitigate such problems, adopt appropriate safeguards to protect the environment. Likewise, avoid pond development in environmentally critical areas such as mangrove areas, marine parks, and reserves, and sanctuaries. If possible, use teaseed cake/powder instead of strong chemicals in controlling pests and predators in fishponds. If chemical pesticide is used, count five to seven days before flushing pond water into the river to avoid polluting the river and poisoning other aquatic organisms. Futhermore, avoid overfeeding the fish with commercial feeds. Decaying uneaten feeds can pollute water and pond environment.

Plant mangroves or other trees on the dikes to strengthen them and to avoid erosion. Dikes can also be planted to cash crops, e.g. string beans, kamote, okra, and peppers.

References

Support services

Technical assistance can be requested from the Bureau of Fisheries and Aquatic Resources (BFAR-DA) and the Coastal Environment Program of the Department of Enviroment and Natural Resources (CEP-DENR).

For seminars and training:

Agri-Aqua Network International
(+63 2) 839-1772 / 839-1782 / 837-0023 / 837-0033
email: webmaster@aani.com.ph
Web: http://www.aani.com.ph

For more information contact:

PCAMRD - Philippine Council for Aquatic and Marine Research and Development
Department of Science and Technology (DOST)
Jamboree Rd., Brgy. Timugan, Los Baños, Laguna
Tel. No.: +63(49)536-5578, 536-5579, 536-1574
Telefax : +63(49)536-1582
E-mail: pcamrd@laguna.net
Web: http://www.pcamrd.dost.gov.ph

PCAMRD Liaison Office
2nd Floor, Rm. 205 PTRI Bldg. Gen. Santos Ave.,
Bicutan, Taguig, Metro Manila, Philippines
Telephone Number: +(632)837-2071 up to 82 local 2430

BFAR - Bureau of Fisheries and Aquatic Resources
Arcadia Building,860 Quezon Avenue
1103 Quezon City, Philippines
Tel No. : +63(2)3725043
Fax No. : +63(2)3725048
Email : info@bfar.da.gov.ph
Web:  http://www.bfar.gov.ph