How We Recently Stocked our Pond with Milkfish (Bangus) Fry

How We Recently Stocked our Pond with Milkfish (Bangus) Fry

In January of 2019, one of our two grow-out ponds (we call it Main Pond) contained near market-size milkfish (bangus). The other (East Pond) is free of bangus but teems with tilapia.

Plan was to take out the market-size bangus from the Main Pond and send the undersized ones to the East Pond next to it.

My harvest team cleared the East Pond of tilapia and mudfish to prepare it for the bangus.

Sweeping the Main Pond three times from end to end with a large seine net (“kalokor”) followed. As planned, harvest workers hauled out the bigger bangus to be sold. The smaller sized ones went to the adjacent East Pond where it will be grown for another 6 weeks or so.

You can view the 5-part videos on harvesting activities by clicking the links below for Parts 1 to 4.

https://youtu.be/PIoM1XdwYcg

https://youtu.be/PF5XcQ5j53k

https://youtu.be/PDTRVmkpNoA

https://youtu.be/dNG_KXFSTNk


Part 5 is shown below.





Pond Draining (“Limas”)

After the harvest, we drained the Main Pond of water. The night before, workers pumped out half of the water and swept the pond using a small kalokor net (“daklis”). This operation was repeated multiple times before dawn to catch several drums of remaining tilapia.

As the early morning sun rose, pond workers pumped out more water followed by hand picking of fish (“kemel”) when pond water was almost drained out and muddy bottom nearly exposed.

Around the area of the water pump where it’s deepest, remaining water from various parts of the pond flowed naturally and converged. It’s in this remaining waters or catchment area where the mostly tilapia fish took refuge.

The pond workers then swept the waters toward the catchment area using a device called “sikop” - bamboo slats or screen. Workers moved the "sikop" gradually toward the catchment area, where another set of bamboo slats awaited.

To prevent the tilapia from slipping out, another worker or two built an improvised canal by piling mounds of mud at the sides of the canal while the moving “sikop” approached along the canal. When the two sets of “sikop” met at the catchment area, the tilapia were trapped. Workers then scooped them out with a scoop net (“tapigo”) into half plastic drums that later went to the delivery area onto a waiting truck.

You can view the 5-part videos on Pond Draining by clicking the Youtube links below (Parts 1 to 5), respectively.

https://youtu.be/AgyetiQKS9Q

https://youtu.be/XMUcCq5IT8g


https://youtu.be/JnsQk0Vgl8M

https://youtu.be/sXVnx2XN03M

https://youtu.be/mA8UHUMDNnc

For Part 6 of 6, pls. click below




Pond Preparation

After the Main Pond was drained of water and all tilapia taken out (including the smaller ones picked up by neighbors who were allowed to scavenge (“kambog”) for remnant fish), we did the following pond preparation activities:

a. Exposure of pond bottom to sun

b. Tilling of pond (sweeping thorny branches of bamboo or camachile tree through the muddy bottom)(team failed to do this)

c. Sanitizing or poisoning of pond bottom using organic teaseed

c. Applying 30 sacks of chicken manure to fertilize the pond

d. Applying supplemental fertilizer 16-20-0

You can view the 2-part video on the above activities by clicking the Youtube link below for Parts 1 and 2, respectively.

https://youtu.be/gkQj_9bJV2Q


https://youtu.be/Rp5Xy8ScG0E


Stocking of Milkfish (Bangus) Fry

After our grow-out pond was drained and the pond prepared, water slowly seeped back in. Soon, pond water reached the level suitable for stocking of bangus fry.

a. Addressing Water Salinity

The only problem is how to increase the salinity of the Main Pond knowing that young bangus fry are salinity sensitive. I read that 7 day old bangus fry only tolerate 16 to 20 ppt (parts per thousand) salinity, while older fry can tolerate lower salinity. We do know that ours have much less, probably zero to 3 ppt.

Also it’s only January. From most growers' experience we know that November, December, January and February are considered cold months for bangus ponds. As such, pond waters are considered too cold for bangus fry to thrive. Hardly anyone dare to stock bangus fry in these cold months.

As to salt water, we normally rely on the opening of the village canal (where six or seven of us pond operators get brackish water). But this will happen only in April or May. I also considered applying rock salt.

But there was a better solution – build a deep water well, from which we can pump out salty water. For details, click this.

b. Increasing Pond Water Temperature

It was still February (an off month for fry stocking, with pond waters still "cold").To make the pond more conducive to bangus fry stocking, we applied 20 sacks of chicken manure. Immerse them, not pour the contents. This will make the pond waters warmer and thereby increase the chances of the fry to survive.



c. Installing Protection Against Bird Attacks

As deterrent to bird attacks, we also covered the entire pond with nylon strings or twines. With two thicker strings along the opposite length of the pond serving as anchor lines, we tied 0.5mm nylon twines across the width of the pond.

Flocks of predatory birds that normally fly above the pond (like the white heron or egret – “dulakak” in Pangasinense) avoid ponds covered by such strings and stay out as a result.



d. Installing of Gill Net (“Tabal”)

While we were installing the nylon twines, our pond workers noticed mudfish (“dalag”) a voracious predator of bangus, especially the young ones. This was surprising because we just poisoned the ponds very recently. But that’s how sneaky the mudfish is. I then asked one pond worker to install gill net (“tabal”) to catch the mudfish.

At first we used it as a moving trap, that is, swept the gill net across the full length of the pond. We caught 3 mudfish as a result.

After that, I had the gill net retained in place at the middle, as a stationary trap, in case other mudfish crawls its way again back into our pond from the adjacent fresh water ponds.

All these measures are aimed at increasing the survivability of the batch of bangus fry that we were about to stock in an “off-month".



Bangus Fry

We bought 28 bags of bangus fry, which are relatively larger in size and expectedly tougher compared to the typical 7 day old fry we typically buy. We decided to go for the bigger fry in view of the timing of fry stocking (it’s only February) and waters are still cold. It was our first time to buy and stock fry in the “cold” months. Hopefully, the bigger fry will have a better chance to survive in this weather. And to grow into fingerlings in two months to be sold to a ready market of fish pen/cage and grow-out pond operators.

Although the fry were reoxygenated by the fry importer upon arrival in Binmaley, Pangasinan we decided to replenish each bag with fresh oxygen before letting them out into the pond.

Before that, actual pond water was added to each bag at the supplier to gradually acclimatize the fry. Same thing was done right before they were stocked. Workers poured bag contents into Styrofoam boxes and added pond water.

Finally, the fry were stocked in the pond at about noon, when the sun was at its highest and pond water warmed up. 



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