28 SEPTEMBER • WORLD AQUACULTURE • WWW.WAS.ORG newly-hatched Artemia nauplii at ten individuals per milliliter. About 30% of the water in the tank should be changed daily. At around day 7-10, farmers can continue feeding the larvae with Artemia nauplii or shift to water fleas. However, beginning at day 10 larvae are fed with a SEAFDEC/AQD formulated diet. It is also recommended to change 50% of the water daily from day 10 onwards before transitioning to the nursery system at day 15. Grow-out in ponds begins with the preparation of the pond itself. The pond is drained and dried for 2 weeks before applying lime and organic manure. Once applied, the pond is surrounded with a fence and filled with water that is allowed to settle for 7 days before applying inorganic fertilizer and urea. The water depth is then further increased up to 60 cm in order to acclimate and stock the fingerlings, which will initially be fed daily with 5% of total biomass, before gradually reducing by 0.5% monthly up until the fifth month. Just before harvesting the catfish, after 3-5 months, some are sampled and cooked to detect off-flavors. Finally, the catfish are then placed in a tank with running water where the customers can choose individual fish (Surtida and Buendia 2000; Brown 2023). Traditional vs. Modern Catfish Farming Methods The stability of traditional catfish farming methods has gained the trust of many farmers over the years. More than its reliance on natural resources, its techniques are rather simpler and less costly to implement. In this method earthen ponds (Figure 2), which are easily constructed by digging, are filled with natural water sources such as ground water. The traditional method utilizes natural food sources like chicken byproducts that are fed directly to the catfish. One farm in Halayhayin, Rizal called Get Farm practices the use of aquatic plants such as duckweed and azolla (Figure 3) as catfish feeds as it is rather cheaper and more sustainable. By using these feeds, traditional farmers can ensure proper growth catfish despite using less formulated commercial feeds. In the same farm, they also practice a natural and traditional breeding method that has not been done for some time in other farms. This natural propagation involves putting one male and one female on a net placed in a small, isolated pond and allowing them to breed overnight by stimulating with hairlike structures called Cabonegro (Figure 4). High survival rates are associated with this method. Given the effectiveness of traditional catfish farming, modern farming techniques involving sustainable practices are rarely reported in the literature, at least in the Philippines. These ecofriendly practices exhibit promising results as they not only protect the environment but also increase fish yields, even in indoor production. However, the trade-off of such techniques lies in costs that ultimately outweigh the benefits, especially for local farmers. An example of this would be the Recirculating Aquaculture System (RAS), which reduces the need for a large amount of water and decreases the disposal of wastewater. Aquaponics has piqued interest, but the set-up can be a bit expensive as it requires specific equipment to function. Although not entirely similar to Aquaponics, the Quezon City University Aquaculture Department (QCUAD) has practiced the same mechanism daily in which the wastewater from a catfish pond is used to water plants while it is then refilled with collected rainwater (Figure 5). More than just water management, sustainable practices are also applicable to the formulation of feeds. Traditionally, widely used fish feeds (Figure 6) in aquaculture were made from wildcaught fish, which can promote overfishing. Thus, the use of plantbased feeds is gaining popularity as it also offers a balanced diet while being cost-effective and easier to produce. Insect-based feed is also being studied by researchers in QCUAD (Figure 7). It is more sustainable, as insects are considered a renewable source. While modern catfish farming has several positive implications, its breeding method is rather unsustainable and poses risks to animal welfare. In recent years, artificial propagation has been done by most farmers to attain faster breeding. However, this method requires killing male breeders to extract testes, which are mixed with eggs produced from female catfish previously injected with pituitary gland extract. This artificial fertilization involves controlled conditions until the eggs hatch, to ensure a high success rate. Detriments of Catfish Farming Despite proper management of the pond, catfish diseases are inevitable. In the Philippines, the major enemy of the local farmers FIGURE 4. Materials used for traditional breeding: Cabanegro (left) and nets (right). Photo credit: A. Olarte.
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