Umbellaria, a highly valued freshwater fish, is gaining popularity among consumers due to its high economic and nutritional value. In recent years, aquaculture has seen rapid growth in Wuyi, with seedling cultivation becoming an increasingly important focus. Below are some key techniques for raising Umbellaria fry, tailored for local farmers:
**I. Selection and Rearing of Broodstock**
The best time to collect broodstock is in September, though selection can also be done in late March or early April. Choose wild or farmed black buckwheat that is at least two winters old, with a weight of 0.75–1.25 kg. Ensure the fish are healthy, free from disease, and without injuries. Place them in a dedicated pond, with one pair per 10 square meters. Before introducing the broodstock, thoroughly clean and disinfect the pond, and disinfect the fish with a mild solution. Maintain a 1:1 male-to-female ratio.
Once spring begins and water temperatures rise to around 15°C, start feeding the broodstock with small amounts—about 1% to 2% of their body weight. Gradually increase the feed as conditions stabilize. When the environment is favorable, the broodstock will enter a more intensive rearing phase. To stimulate gonad development, regularly flush the water while feeding them 6–8% of their body weight daily. Spawning typically begins in May when the water temperature exceeds 20°C.
**II. Artificial Breeding Techniques**
Artificial spawning is usually conducted between May and June. Select females with swollen, soft bellies, visible ovaries, and protruding genitalia. Males should have a deep purple-red coloration, with neatly arranged white spots on their dorsal fins. The more white spots present, the better the quality.
A common method is to administer a single thoracic injection. The dosage is 6 mg DOM + 15 mg LRH-A per kg of female body weight, while males receive half the dose. Spawning can occur in hatching tanks, concrete pools, or earthen ponds. Hatching cylinders yield the best results. After cleaning and disinfecting the incubator, add fresh water and treat the fish with 1 ppm malachite green. Place a small amount of water peanuts in the nest. Once injected, place the broodstock in pairs inside the cylinder, covered with a fine mesh net to prevent escape. Use water flow or microfluidic systems to control the timing, which generally takes 27–35 hours at 22–23°C and 24–30 hours at 24–25°C. Spawning occurs in a quiet, low-light environment; any disturbance may stop the process. Eggs are collected 12–14 days after spawning, with unfertilized eggs removed before hatching.
**III. Artificial Hatching**
Fish eggs can be hatched using a hatching cage (40cm x 100cm x 50cm) with a microfluidic system, holding about 10,000 fertilized eggs per unit. Alternatively, they can be hatched in hatchery pools (3m x 4m x 0.8m), with 40,000–50,000 eggs per pool. Hatching success depends on egg fertility and water quality. Key steps include preventing water mold, maintaining clean water, handling eggs gently, and avoiding sudden temperature changes.
**IV. Seedling Cultivation**
While hatching is relatively easy, raising fry is challenging, requiring careful management and attention to detail. Survival rates are often low if not properly managed.
**1. Larval Rearing**
After 4–5 days, larvae begin feeding on zooplankton smaller than 200 μm. Feed small amounts every 4 hours initially, gradually increasing the number of feedings and reducing frequency. Transition to twice-daily feeding by day 3–4. By day 7–10, larvae may cluster and show signs of "red worms." Agitate the water to improve survival. Remove unfertilized eggs and debris daily, change water regularly, and monitor for fungal and parasitic infections. By day 5–6 (9–10 days post-hatch), fry reach 1–1.4 cm and become more active, ready for normal feeding. Adjust density and move to summer fish species cultivation.
**2. Summer Fish Species Cultivation**
Summer fish species can be raised in concrete tanks, typically 4m x 3m x 0.8m, equipped with inflow, outflow, aeration, and feeding stations. A plastic shed is recommended above the tank to protect from sunlight and rain, ensuring stable conditions. Stocking density ranges from 400–500 fry per square meter in ponds, up to 1,000 in microfluidic systems. Initially, use live zooplankton, then introduce dead zooplankton and other supplements like Yeast protein or fishmeal when needed. Feed small portions frequently to maximize survival. Monitor water quality and ensure proper aeration for optimal growth.
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