How to Increase Milkfish Production through Adequate Pond Bottom Preparation
The step by step procedure compiled here started to shape during my field work (early 1990) in Negros Occidental (Cadiz and Silay City) while doing my Master Degree in Agriculture (major in Soil Science). I did my MS Degree Thesis field experiment in Cadiz City, Negros Occidental. While in Negros, we worked on prawn ponds particularly those setting on acid sulfate soils. As a “Soils Man”, I and my colleague at the Bureau of Soils and Water management, Dr. Perfecto P. Evangelista focused on the improvement of prawn pond bottom soils. While doing works in the area, we learned and tried several technologies. Most of these technologies are from the Bureau of Fisheries and Aquatic Resources (BFAR) and SEAFDEC, while others are indigenous in the area.
Some of the technologies were modified to suit in the specific site. We religiously noted the combinations we tried and the modifications we did. Then we tried to come up with the general procedure for milkfish production. Specifics of the methods depend on the site characteristics which vary from one location to another. Our works were also inspired by the earlier work of Dr. Paul Singh on acid sulfate soils. The knowledge/technologies gained in Negros were tested first in-part in Hagonoy, Bulacan in the Milkfish production ponds of Mr. Marcelo Crisostomo while I’m advising several students from the Far Eastern University doing their BS Thesis. I also have a chance to validate the methods in Quezon province while working on “Toxicity Study”. To date (October 2006), the technology is being used in La Union, Pangasinan Milkfish production ponds.
In general, ideal pond site for good milkfish production requires high tidal range; can hold water at least 1 meter depth; with good water quality (constant salinity and temperature; long dry season-milkfish grow bigger during the dry season); with sandy clay loam or silty clay loam soil; away from domestic and industrial pollution; and with sufficient clean fresh water supply. In terms of pond design, ponds must have separate inlet and outlet gates so that incoming water is clean and kept separate from pond effluents. Pond bottom must be even and flat but inclined towards the outlet gate so that the ponds can be drained properly.
Step by step procedure to improve milkfish pond production (Note the quantity of material stated here could vary depending on the site characteristics).
|
No. |
Activities |
Days Required |
Details |
|
1. |
Pond draining |
1 |
This can coincide during harvesting.
Note: To facilitate draining and harvesting of stock, construct inside-pond diagonal canal as drain canal with slight down slope towards the outlet.
|
|
2. |
Pond drying |
2 – 7 |
Depending on weather condition; it can last for 2 weeks; dry the pond bottom until the soil cracks; this is to oxidize the soil at the same time kill predators or the unwanted species like the snails.
|
|
3. |
Pest predator control (unwanted species i.e. snail Cerithidea cingulata, and bangungon)
|
2 – 7 |
Simultaneous with pond drying; use tobacco dust @ 250 to 500 kg/ha); spread evenly in the pond bottom; if fresh water is available it can be used to flush in the pond and kill the snails; manual removal is also an alternative; Ammonium sulfate application is another option. |
|
4. |
Liming |
|
This is optional; only if the pond bottom soil pH is lower than 6.8. Use CaCO3 at rate depending on the soil pH. Very low pH will require higher rate.
|
|
5. |
Washing |
8 |
Do it 2 to 3 times; to remove substances i.e. tobacco dust that can affect water quality; it will also remove unwanted dead species.
|
|
6. |
Tilling/ cultivation |
9 |
This should be done at least once a year during the pond preparation or after every two cropping. To improve oxidation, decomposition and for good growth of lablab (natural food).
|
|
7. |
Organic Fertilization |
10 |
To increase nutrient N content of the soil and improve the growth of lablab; Use 1.5 to 2.0 T/ha of chicken dung depending on the soil analysis; ideally for good growth of lablab, pond bottom soil must have 3% or more O.M.; >18 ppm Olsen P and >75 ppm extractable K by Hot H2SO4 method and 6.8 to 8.6 soil pH.
|
|
8. |
First water intake |
11 |
5 cm depth; Water intake should be gradual to avoid disturbance of mat of lablab (will detach and float) that will start to form. Change in color of water from clear to brown, yellow brown and greenish color indicates development of lablab.
Note: Install fine-meshed screen (bastidor or lumpot) at the gates to prevent entry of wild species or possible escape of stock.
|
|
9. |
Inorganic fertilization |
14 |
15 kg Urea/ha; this should improve the decomposition of organic fertilizers applied and consequently increased the N content of the soil. Rate of fertilizer would depend on the soil analysis.
|
|
10 |
Second water intake |
18 |
10 cm depth |
|
11. |
Inorganic fertilization |
18 |
25 kg/ha 16-20-0; immediately after 2nd water intake. |
|
12. |
third water intake |
25 |
15 cm depth |
|
13. |
Fertilizer dressing |
25 |
25 kg/ha Urea; immediately after 3rd water intake |
|
14. |
Fourth water intake |
32 |
20 cm depth |
|
15. |
Fertilizer dressing |
32 |
25 kg/ha 16-20-0; |
|
16. |
Fifth water intake |
39 |
25 cm depth |
|
17. |
Fertilizer dressing |
39 |
25 kg/ha Urea; |
|
18. |
Sixth water intake |
45 |
30 to 40 cm depth |
|
19. |
Monitor water quality |
45 |
Parameters to be monitored:
DO should be 3-5 ppm; measured by DO meter;
pH should be 6.8 to 8.7 (optimum level 7.2 to 7.6) measured by pH meter;
Salinity 10 to 32 (optimum 24 to 26 ppt) by refractometer;
Temperature 20 to 33 oC (optimum 26 to 30) by thermometer;
Turbidity at 50% by Secchi disc (ex. when the water depth is 40 cm, at 20 cm water should be turbid).
Note: Not enough dissolved oxygen can cause stress, fish tend to swim in circles at the surface, and they appear to be gasping for breath.
|
|
20. |
Fish stocking |
46 to 50 |
Stocking should be done at the cooler time of the day.
Density that should be observed at different growth stages:
1 to 30 days old fry (size of 0.02 to 0.5 g) = 40/m2
31to 60 days old fingerlings (0.5 to 10 g) = 5/ m2
61 to 90 days juveniles (10 to 40 g) = 2/ m2
91 to 150 days grown fish (50 to 250 g) = 1/ m2
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For more info:
Call: Dr. GavinoIsagani P. Urriza
At: (02) 923-04-59 or email at: gurriza258@yahoo.com or visit us at: conservationist.wordpress.com

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