Umbellaria is a highly valuable freshwater fish, both economically and nutritionally, making it a popular choice among consumers. In recent years, aquaculture of this species has gained momentum in Wuyi, with seedling cultivation becoming increasingly important. Here’s a detailed guide on the breeding techniques for Umbellaria seedlings, tailored for farmers:
**I. Selection and Cultivation of Broodstock**
The best time to collect broodstock is in September of the same year, though selection can also be done in late March or early April. It's recommended to choose wild or farmed black buckwheat that is at least two winters old, with a weight of 0.75 to 1.25 kg. The fish should be healthy, free from disease and injury. They are placed in a special pond, with one pair per 10 square meters. Before introducing the broodstock, the pond must be thoroughly cleaned and disinfected, and the fish themselves should be treated with disinfectants. The male-to-female ratio should be 1:1.
Once spring arrives and water temperatures rise to around 15°C, feeding begins. The initial feeding amount should be about 1% to 2% of the fish’s body weight, gradually increasing as the fish adapt. When conditions are favorable, the broodstock enters an intensive care phase. To support gonad development, regular water flushing is essential, combined with daily feeding at 6-8% of their body weight. By May, when the temperature exceeds 20°C, spawning typically begins.
**II. Artificial Spawning**
Artificial spawning of Umbellaria usually occurs between May and June. Female fish should show a swollen, soft belly with visible ovaries and a distinct central groove, while the genital opening is protruding. Males should have a deep purple-red body color, with neatly arranged white spots on their dorsal fins—more spots indicate better quality.
A common method involves a single thoracic injection. The dosage for females is 6 mg DOM + 15 mg LRH-A per kg of body weight, while males receive half that amount. Spawning takes place in hatching tanks, concrete ponds, or earthen pools, with hatching cylinders yielding the best results. After cleaning and disinfecting the incubator, new water is added, and the fish are treated with 1 ppm malachite green. A small amount of water peanuts is placed in the nest. Once injected, the broodstock is placed in pairs inside the incubator, covered with a fine mesh to prevent jumping. Water flow or microfluidic systems can be used to regulate conditions. At 22–23°C, spawning lasts 27–35 hours, while at 24–25°C, it takes 24–30 hours. Spawning requires a quiet, dim environment; any disturbance may halt the process. Eggs are collected 12–14 days after spawning, with unfertilized eggs (white eggs) removed and placed in the incubator for hatching.
**III. Artificial Hatching**
Fish eggs can be hatched using a hatching cage (40cm x 100cm x 50cm) with a microfluidic system, holding up to 10,000 fertilized eggs per box. Alternatively, they can be hatched in hatchery pools (3m x 4m x 0.8m), with 40,000 to 50,000 eggs per pool. The success of hatching depends on egg fertilization rates and water quality. Preventing water mold, maintaining clean water, handling eggs gently, and avoiding sudden temperature changes are crucial for high hatching rates.
**IV. Seedling Cultivation**
While Umbellaria eggs are easy to produce and hatch, the fry are challenging to raise, requiring careful management and high survival rates. Even minor mistakes can lead to losses.
**1. Larval Rearing**
After 4–5 days, larvae begin feeding on zooplankton, with particles smaller than 200 μm. Small, frequent meals are given, gradually increasing the number of feedings over 3–4 days before reducing them. Transitioning to two feedings per day is ideal. By day 7–10, larvae often cluster, leading to "red worm" issues. Gentle water agitation helps improve survival. Unfertilized eggs and membranes should be removed promptly, and the water should be changed daily. Controlling fungal and protozoan infections is essential. By day 5–6 (9–10 days post-hatching), when fry reach 1–1.4 cm, they become more active and ready to feed normally. As they grow, they are reared in larger groups, density is reduced, and they move into summer fish culture.
**2. Summer Fish Culture**
Summer fish culture is typically done in concrete tanks measuring 4m x 3m x 0.8m, equipped with inlet and outlet systems, aeration, and feeding tables. A plastic shed is recommended to protect against direct sunlight and rain, ensuring a stable environment for easier management and disease control. Stocking density ranges from 400–500 fish per square meter in ponds, up to 1000 fish per square meter in microfluidic systems. Initially, fresh zooplankton is used as feed. Once fry exceed 2 cm, dead zooplankton and other supplements like Yeast protein, fishmeal, or wheat flour can be added. Small, frequent feedings help improve survival. Maintaining good water quality and oxygen levels is essential throughout the process.
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