The culture of natural food for the hatchery of marine fishes is well established. The protocol for the culture of phytoplankton like Chaetoceros and Skeletonema for the larval rearing of tiger and white shrimps and the culture of the rotifer as first food for most marine fishes – like milkfish, seabass, snappers, groupers, and siganids – have been an integral part of their hatchery operations. Feeding the newly hatched shrimps and fish larvae with these natural food has been shown to be the only method necessary to achieve good survival rates of shrimp postlarvae and fish fry.
It cannot be said however, that the same is true for freshwater fishes. At present, no commercial freshwater fish hatchery in the country cultures natural food. The reason perhaps is because tilapia, the most popular cultured freshwater fish in the Philippines, can be successfully larval reared using commercial fry feed due to the big size of its hatchlings. On the other hand, other fishes like carps, aquarium fishes and even catfishes are stocked directly to nursery ponds a few days after hatching. With this method, it is considered fortunate to have recovery rates of 20 percent because on the average, only about 5 percent can be achieved.
Despite the breakthrough in the induced spawning technology, the lack of proper larval rearing techniques could be the main reason why the freshwater aqua-culture industry, including the freshwater aquarium fish industry in the Philippines, has lagged behind.