Culture of Milkfish Using Semi-Intensive System Part 2

Figure 6. Nutrient Requirements of Milkfish Feed

Nutrient Suggested level Typical source
Crude protein 25-40% Fish meal, soybean, corn, glutenmeal, ipil-ipil
Crude fat 7-10% Vegetable and fish meal
Nitrogen Free-extract (Digestible carbohydrates) 25% Yellow corn, cassava meal, rice and wheat bran, flour
Crude fiber <8%
Vitamin, minerals mix 3-6%
Metabolized energy >3,200 kcal/kg

Figure 7. Water Quality Parameter (Paramater – Optimum Level)

  • Dissolved oxygen concentration – 3-5 ppm
  • Temperature – 22-35 °C
  • pH level – 6.8 to 8.7
  • Salinity – 18 to 32 ppt
  • Turbidity – 0.5 m

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

  • Avoid areas with problems of domestic, industrial, or agricultural pollution.
  • Ensure sufficient supply of clean water.
  • Put up independent water supply.
  • Apply complete drying, and if indicated, liming of sediments.
  • Always stock good quality fingerlings.
  • Practice right stocking density according to management capability and environmental conditions.
  • Maintain high quality water supply.
  • Always ensure sufficient water exchange.
  • Avoid adding large volumes of new water that may contain pollutants (setting of water in reservoir before use can improve its quality).
  • Set regular water quality monitoring (e.g., turbidity, water color, dissolved oxygen, pH and temperature) activities.
  • Anticipate adverse weather conditions. Sudden rain or thumderstorms during hot day may present dangers as well as sudden changes in water temperature which may also result in some fish kills.
  • Observe extra precaution to minimize the possibility of dike wash-out flooding and the like.
  • Apply controlled feeding and feed fish only with high quality food.
  • Monitor survival rate, biomass, growth and health.
  • Quarantine new stock.

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 tea-seed 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. Furthermore, 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.

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 Environment and Natural Resources (CEP-DENR).

For more information contact:

PCAMRD – DOST
Jamboree rd., Brgy. Timugan, Los Banos, Laguna
Tel. No.: (049) 536-5578/5579/1574
E-mail: [email protected]
Web: www.pcamrd.dost.gov.ph

PCAMRD Liaison Office
2nd Floor, Rm. 205 PTRI Bldg.
Gen. Santos Ave., Bicutan, Taguig City
Tel: (02) 837-2071 up to 82 local 2430

BFAR – Bureau of Fisheries and Aquatic Resources
Arcadia Building 860 Quezon Avenue, Q.C.
Tel No. : (02) 372-5043
Email : [email protected]
Web: www.bfar.gov.ph

source: da.gov.ph

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