Third, fry management
After the larvae leave the nest, they begin to feed and gradually shift from internal to external nutrition. Therefore, it is essential to pay close attention to fry management during this critical period. Maintaining clean water and providing a consistent and adequate food supply are key to ensuring their healthy development. Fry feeding should start once the fry have fully left the nest. Natural or cultured plankton is considered the best initial food, although artificial feed can also be used as an alternative. In the first week after swimming, fry should be fed salmon powder, with 6 to 7 feedings per day. Feeding should begin at the edge of the pond and gradually move toward the center. Overfeeding must be avoided, as it can severely pollute the water and negatively impact the health and survival rate of the fry. By the second week, live leeches can be introduced, with 3 to 4 feedings daily. In the third week, as the fry grow, whole worms can be offered depending on their size and condition. Whenever possible, leeches should be prioritized, as they play a vital role in promoting healthy growth. Water quality management is equally crucial during the fry stage. Maintaining clean and fresh water is essential for their well-being. Adding probiotics to the hatchery not only improves water quality but also serves as a nutritious starter feed for the fry. Water should be added gradually to the fry pool. When the fish are weak, extra care must be taken when changing water. Sudden changes in water flow, temperature, or other water parameters can stress the fry and even lead to mortality. If local water changes are necessary, the water should be drained slowly, and a fine mesh gauze (50 mesh) should be placed over the discharge pipe to prevent fry from being lost. Fourth, fry selection Fry can be sorted when they reach a body length of 1 to 1.5 cm, typically around one month old. The sorting process includes the following steps: 1. After several passes with a 50-mesh nylon net, when few fry remain in the pond, drain the water and use a water pump to collect the remaining fry. 2. Avoid using fishing nets, as they can harm the delicate fry. Instead, use plastic pots or ceramic bowls filled with water to safely catch them. 3. During the first sorting, remove any fry with deformed tails, such as those with single tails, split tails, or curled ends. If breeding specific varieties, also eliminate those with abnormal scales. 4. When the fry grow to 2–3 cm, a second selection can be made. At this stage, focus on removing individuals that do not meet the variety's standards in terms of size and appearance. For high-quality fish farming, a final and more rigorous selection should take place when the fish reach 5–6 cm. Select fry with a long, streamlined body, strong tail fins, and good coloration. Those that do not meet the desired traits should be removed and culled. This careful selection ensures that only the healthiest and most desirable fry are kept for further rearing.Industrial Grade Formates,Ammonium Formate,Formic Acid Potassium Salt,Potassium Formate
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