Grass-fed fish farming is an economical and efficient method that offers a short production cycle and good returns, making it a promising approach for aquaculture. However, despite its advantages, several challenges remain in the southern regions of China that need to be addressed effectively.
First, there are significant issues with fish farming in the South:
1. **Limited Area of High-Quality Forage Grass**
Although many fish farms have planted grasses like Sudan grass and ryegrass, the area is small, and the quantity of forage available is insufficient. In Hunan Province, for example, the current forage supply only meets about 1/5 to 1/4 of the fish’s dietary needs. This shortage forces farmers to rely on weeds or supplemental feeds, which not only increases costs but also affects fish growth and quality. In reservoirs, the lack of forage results in low fish yields—often just 5 to 8 kg per year per acre.
2. **Monoculture of Grass Species**
For decades, most southern fish farms have relied heavily on a few species such as Sudan grass and ryegrass, which together occupy about 80% of the grazing land. Continuous planting has led to soil degradation and reduced productivity. Ryegrass, for instance, struggles during hot and dry months, leaving a gap in forage supply when fish require more food. This often leads to increased use of commercial feed, which raises costs and may compromise fish size and quality.
3. **Degradation of Grass Species**
Over time, the lack of proper selection and breeding of forage grasses has resulted in lower yield and poor quality. Once, Sudan grass could be harvested 6–8 times a year, producing up to 0.5–0.7 tons per acre. Now, after just 2–3 cuts, the grass dies, and the annual yield drops to 0.2–0.3 tons per acre. The growing period has also been shortened by 50–60 days.
4. **Pest and Disease Problems**
Sudan grass is frequently affected by rust, leaf spot, and locust infestations. These diseases cause large losses, with up to 40–50% of the forage becoming inedible. When fish consume diseased grass, their health is compromised, increasing disease incidence and reducing overall productivity.
5. **Lack of Scientific Management**
Many farmers lack the knowledge to properly manage forage grasses. They often choose unsuitable species, fail to implement proper cultivation techniques, and cannot identify harmful weeds. This leads to accidental poisoning of fish and slow adoption of new, high-quality forages and advanced methods.
To improve grass-fed fish farming in the South, several strategies should be implemented:
1. **Promote High-Quality Forage Species**
Degraded grass varieties must be replaced with improved ones. New species such as U.S. dwarf elephant grass, hybrid elephant grass, flat-leaf bull whip, hybrid Pennisetum, and Emperor grass offer higher yields, better quality, and greater resilience. These grasses can thrive for years with minimal maintenance and provide safe, nutritious feed for fish.
2. **Combine High and Low Yield Grasses**
Intercropping high-yield forages with legumes like alfalfa can increase total forage production by 20–30%, while also addressing the summer forage shortage from July to October.
3. **Implement Scientific Cutting Practices**
Proper cutting techniques are essential. Forage should be cut at the right height (e.g., 100 cm for tall grasses), and cutting should be avoided during droughts or before heavy frosts. Tools must be kept clean to prevent the spread of diseases, and feeding should be done consistently and in measured amounts.
4. **Expand Forage Land Use**
The southern region has vast potential for expanding forage areas. By utilizing riverbanks, pond edges, and reservoirs, farmers can significantly increase grassland coverage. Ideally, every acre of water should be matched with one acre of forage, especially for cage culture. The goal should be to grow 3 acres of forage for every 1 acre of fish in cages.
By addressing these challenges and implementing better practices, grass-fed fish farming in southern China can become more sustainable, productive, and profitable.
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