Feeding and feeding management are essential components of the overall culture technology for giant salamanders. The quality of feeding and management directly impacts the growth, development, and health of adult individuals. There is a strong correlation between the occurrence of polyps, water quality stability, and the survival rate of adult salamanders.
1. **Adult Eco-Physiological Habits**
(1) **Habitat**: In their natural environment, adult giant salamanders inhabit dark springs in the Yinhe River. In artificial breeding settings, they are kept in artificial caves that mimic these conditions.
(2) **Diet**: Adult giant salamanders are carnivorous. Their feed can be divided into two main categories: fresh or frozen animal-based foods (with low fat content) and artificial compound feeds.
(3) **Water Temperature**: This is a critical factor influencing growth and gonadal development. The optimal range is 16–25°C, with the best range being 18–23°C.
(4) **pH Level**: The ideal pH range for adults is 6.5 to 7.5.
(5) **Lighting**: Giant salamanders are photophobic, meaning they avoid bright light. They prefer a light intensity of 100–500 lux, and their movement patterns are typically nocturnal.
2. **Feeding Methods and Strategies**
2.1 **Types of Feed**
Baby giant salamanders are carnivorous, and their natural diet includes fish, shrimp, frogs, shellfish, loach, and eggs of chickens and ducks. They also consume meat from lamb, beef, rabbit, and quail. Artificial compound feed can be used, such as catfish feed. Specialized compound feed has been developed specifically for giant salamanders. The feed conversion ratio for natural bait ranges from 3.5 to 6.3, while for compound feed it is 2.8 to 3.6. Local feed availability should guide the selection of food sources.
2.2 **Feeding Practices**
To improve breeding efficiency and reduce costs, it's important to understand the digestive and nutritional capabilities of adult salamanders before feeding. This helps determine an appropriate feeding strategy. Proper feeding involves considering nutrition, growth, metabolism, physiological needs, environmental factors, feeding frequency, and feeding principles.
(1) **Feeding Time and Frequency**: Under suitable temperature conditions, adult giant salamanders digest food efficiently. Typically, they are fed once every 2–3 days. When water temperatures drop below 10°C, feeding frequency decreases to once every 5–7 days. Since they are nocturnal, summer feeding is usually scheduled between 8–10 PM, while winter feeding occurs around 6–8 PM.
(2) **Feeding Amount**: Several factors influence feeding quantity, including water temperature, dissolved oxygen levels, water quality, disease status, and feed type and quality. Water temperature is especially important because it affects metabolic activity. At 18–23°C, feeding is most active and growth is fastest. Above 26°C, appetite declines, and at 28°C or higher, the salamander may enter a state of summer dormancy. Under optimal conditions, dissolved oxygen and water quality play a significant role in determining the right amount of feed.
(3) **Feeding Techniques**: Feeding methods should align with the natural behaviors and ecological habits of juvenile salamanders. To maximize feed utilization and reduce waste, the "four-time" feeding method is recommended: timing, location, quality, and quantity.
- **Timing**: Feeding should be done at consistent times based on their nocturnal behavior. For example, feeding is typically scheduled at 10 PM in summer and 8 PM in winter. Adjustments can be made depending on seasonal changes, water temperature, and water quality.
- **Location**: Establishing a feeding spot encourages concentrated feeding, which enhances appetite and reduces feed loss.
- **Quality**: If using artificial feed, it should be stored in a cool, dry place. Oils like fish oil and corn oil are often added to enhance protein absorption. The oil content varies with water temperature—5% at 18–23°C, 5–6% at 14–17°C, and none below 12°C. Fresh, clean natural feed such as loach, cod, squid, and poultry eggs is preferred.
- **Quantity**: The amount of feed should be adjusted according to individual size, digestion ability, water temperature, and water quality.
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