Big silver fish pond breeding technology

The habits of large silverfish in the pond are essential to understand for successful aquaculture. 1. **Habitat Behavior** Large silverfish typically reside in the middle and lower layers of the pond. They rarely come to the surface unless there is a lack of oxygen. In areas with aquatic plants, they often hide among them, and when disturbed, they burrow into the mud at the bottom. Juvenile fish exhibit strong phototaxis, meaning they are attracted to light. This behavior can be used at night to gather them using lights, which helps monitor their growth and feeding patterns. However, adult fish do not show this attraction to light. 2. **Feeding Habits** Juveniles begin feeding on the 10th day after hatching, starting with rotifers. As they grow, they gradually shift to larger zooplankton such as nauplii, copepods, and cladocerans. Eventually, they transition to a carnivorous diet, primarily consuming small fish and shrimp. This dietary change is crucial for their development and must be managed carefully. 3. **Breeding Habits** In ponds, large silverfish can mature and spawn naturally. Their reproductive cycle is similar to that observed in natural water bodies. In the middle and lower reaches of the Yangtze River, spawning typically peaks between late December and early January. Ponds with hard bottoms and aquatic vegetation tend to have higher fertilization rates—often reaching 80–90%. **Pond Conditions** Ideal ponds are old, clean, and free from pollution. They should be sheltered from direct sunlight and have good drainage. A single pond should range from 3 to 5 acres, with a depth of at least 2 meters and a layer of about 0.2 meters of soft mud. These conditions help maintain stable water quality. It’s important to avoid mixing with omnivorous or predatory fish, as they may compete for resources or harm the silverfish. **Seedling Stocking and Cultivation** 1. **Preparation of the Stocking Pond** Before stocking, it's recommended to use water from breeding ponds to introduce rotifers and their dormant eggs. This helps increase food density quickly, which is essential for young silverfish. The process should start two weeks before stocking, with a water depth of around 0.6 meters. 2. **Source of Seedlings** Mature broodstock can be collected from natural waters, and artificial insemination can be performed on-site to obtain fertilized eggs. These eggs are often available from places like Taihu Lake and Dianchi Lake. Hatching is done indoors at temperatures between 4°C and 6°C, taking about 30–40 days. Timing is critical, as releasing fry after mid-February ensures better access to food and improves survival rates. 3. **Stocking Methods** It’s more effective to stock eggs rather than embryos. Eggs should be introduced a week before hatching. For a 1-acre pond, about 20,000 eggs are sufficient, leading to approximately 30 kg of silverfish after 9–10 months. Overstocking can lead to poor survival due to insufficient food. The pond depth should be around 1–1.5 meters during this phase. 4. **Cultivation Techniques** Larvae depend on rotifers and nauplii for nutrition. If these food sources are not available within 10 days, the larvae may die. Therefore, the pond should be fertilized in advance to ensure adequate food supply. After 10–15 days, the water becomes rich in plankton, providing a suitable environment for juvenile fish. As the fish grow, they consume cladocerans, copepods, and chironomid larvae. Fertilization should be adjusted based on water color and temperature, maintaining a transparency of at least 40 cm. Water depth should be kept around 2 meters for optimal growth. **Adult Fish Breeding** 1. **Feeding** Once silverfish reach 40 mm in length, their appetite increases significantly. To support this, regular fertilization is necessary to maintain plankton density. Fermented manure is commonly used, and a small amount of soy milk can also be added (about 250–500 grams per pond, depending on water quality). 2. **Preventing Floating Heads** Large silverfish require high oxygen levels. Floating heads often occur in polyculture systems, especially when water temperature reaches 20°C. Immediate action is needed to prevent mass deaths. Reducing fertilizer input and avoiding overfeeding can help. If the water becomes too rich, fresh water should be replaced, or aerators can be used to increase oxygen levels. 3. **Diet Transition** As silverfish grow, they gradually shift from zooplankton to a meat-based diet. When fish or shrimp are found in their intestines, it indicates a dietary change. Introducing small fish and shrimp at this stage can greatly enhance growth. In experiments, introducing egg-holding shrimp in May allowed them to hatch just in time for the silverfish’s feeding transition. 4. **Summer Heat Protection** During hot summer months, maintaining a water depth of at least 2.5 meters is ideal. If this is not possible, shading measures should be taken to reduce heat stress and protect the fish.

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