Key Technical Points and Daily Management Methods for Chinese Giant Salamander Farming

The Chinese giant salamander is the common name for the giant salamander (Andrias davidianus), a Class II nationally protected wild animal. In China, the giant salamander is distributed in all provinces and autonomous regions except **, Tibet, Inner Mongolia, Heilongjiang, Jilin, Liaoning, and Taiwan, China, where no reports exist; it is mainly found in mountain streams and tributaries of the upper and middle reaches of the Yangtze, Yellow, and Pearl Rivers, especially in Sichuan, Hubei, Hunan, Guizhou, and Shaanxi provinces. The giant salamander prefers shade and fears light, and grows relatively slowly; under wild conditions it takes 5 to 6 years to reach sexual maturity and weigh over 500 grams, while under artificial conditions it takes at least 3 years to reach marketable size. Moreover, artificial breeding of the giant salamander is relatively difficult. Therefore, farming is not widespread, limited to a few farms in Jiangsu, Hubei, Guangdong, and other places. However, in recent years, giant salamander farming has received widespread attention and is a premium special-quality species with great potential.

Structure of the Farming Pond

Based on the unique ecological habits of the Chinese giant salamander, the design of the farming pond must take into account the ecological environment suited to its living habits and growth and development. There are two types of giant salamander farming sites: one is an open-air farming pond, and the other is a farming pond in civil air defense facilities and basements. The structures are made of brick, cement, stone, or concrete. The specific structural requirements are:

1. Pond wall structure: The requirements for the walls of a giant salamander farming pond are: (1) watertight, so that it does not leak. (2) Safe and firm, able to withstand the soil pressure around the walls and the pressure of the pond water, without the walls sinking. (3) Must have anti-escape facilities. (4) Inexpensive. The walls of a giant salamander farming pond are generally built with square stones, bricks, or concrete, with cement filling the seams; the walls should be smoothed with cement slurry or tiled. The top of the wall should extend inward 10 cm to prevent the giant salamander from escaping.

2. Pond bottom structure: The bottom of a giant salamander pond is generally first compacted with stones to a thickness of 20 to 30 cm, then filled with small gravel, and finally leveled with concrete. To facilitate drainage, the pond bottom slopes from all sides toward the center at a gradient of about 2%, and then slopes from the center toward the drainage outlet at one corner at a gradient of about 1% to 1.5%.

3. Inlet: The inlet is positioned according to the intake channel, opposite the drainage outlet at the corner of the pond. The inlet should be higher than the pond wall, preferably 60 cm above the ground water surface, and extend 20 cm into the pond. The inlet material can be cement pipe or concrete square, or cast iron pipe or plastic pipe. Regardless of the material used for the inlet, a control device and filter screen must be installed. The control device uses a straight-through stop valve; the pipe diameter size can be determined according to the water volume required by each type of giant salamander pond and the inlet pressure. For juvenile ponds, 100-300 mm can be selected; for adult ponds, 300 to 500 mm can be selected. The filter screen material for the inlet should be stainless steel, and the mesh should also be determined according to the size of the giant salamander pond.

Construction of the Farming Site

The adult giant salamander farming pond is an important environmental condition for giant salamander farming, and is the key period in the commercial farming stage of the giant salamander. In the adult stage, the giant salamander's resistance and adaptability increase, while escape attempts and same-species cannibalism also reach a peak. Therefore, the adult site must meet the physiological characteristics of this stage. More than 5 ponds should be built so that individuals can be farmed separately according to size.

According to local conditions, adult ponds can be built indoors or in civil air defense facilities, or outdoors. The pond area can reach 100 to 2,000 sq m. The area of artificial arcs or burrows in the pond accounts for 2/3 of the adult pond area; the size of the arcs or burrows depends on the size of the adult individuals. For outdoor ponds, in addition to the requirements and facilities of indoor adult sites, shading facilities must be installed. Shading materials can be installed according to local conditions, and the top and all sides of the pond must be fully shaded.

Farming of Adults

Domestically, successful experience and technology have been gained in adult farming. The main farming methods include outdoor farming, basement and civil air defense facility farming, and the factory-based temperature-controlled farming developed by our research. In summary, they are mainly divided into still-water farming and flowing-water farming.

Wild giant salamanders rely on feed from the natural environment as their nutritional basis, so they grow slowly and generally need 5 years to reach adulthood. Artificial farming of giant salamanders creates a good ecological environment and provides nutritionally rich feed, so generally only 2 to 3 years are needed to reach the adult stage.

Because of its high nutritional and medicinal value, the giant salamander has enormous economic development value. Therefore, giant salamander breeding and farming technology will be a key competitive focus of China's aquaculture industry for some time to come, and the giant salamander will also be a key species for future development.

Stocking of Adults

1. Preparation before stocking

(1) Repair and disinfection of the adult pond mainly involves checking the inlet and outlet pipes. Check whether the barrier nets are damaged, check the filter pond, filtration devices, and temperature-control machines for faults and repair them, inspect the adult pond to see whether there is damage and repair it in time, then disinfect the adult pond and stock only after the drug effect has dissipated.

(2) Disinfection of adults: Disinfection of adults mainly prevents water mold disease and bacterial diseases; the disinfection method, drugs, and procedures are the same as for juveniles. When stocking, the water temperature of the adult farming pond should be the same as that of the juvenile pond.

(3) Inspection before stocking: The number and size of adults should be checked so that adults can be graded by large, medium, and small individuals and raised in separate ponds. In this way, adults of the same size grade have basically the same feeding ability and feeding intensity and basically the same growth rate, which can avoid mutual predation caused by mixed farming of different sizes.

2. Stocking density

The stocking density of adult giant salamanders should be determined according to the farming method, technical level, and farming conditions in each place.

Feed and Feeding

Feed and feeding are the central link in the entire giant salamander farming technique. The quality of feeding management has an extremely close relationship with adult growth and development, the occurrence of giant salamander diseases, water quality stability, and adult survival rate and yield.

1. Ecological and physiological habits of adults

(1) Living habits: In the natural environment, adults inhabit places with shaded rivers and dark springs; in artificial farming, they inhabit artificial burrows.

(2) Feed: Adults are carnivorous animals. Feed is divided into two major categories: fresh and frozen animals (but those with excessive fat are unsuitable), and artificial compound feed.

(3) Water temperature: The determining factor for adult growth and gonadal development; the suitable range is 16 to 25°C, and the optimal range is 18 to 23°C.

(4) Oxygen consumption: 20.28 to 32.89 mg/kg per hectare during the day, and 21.69 to 36.24 mg/kg per hectare at night.

(5) PH: The suitable PH for adults is 6.5 to 7.5.

(6) Light: Adults move away from light—that is, they fear light, and require a light intensity of 100 to 500 lux.

2. Feed and feeding methods

(1) Feed types: The giant salamander is a carnivorous animal, and its natural feed resources are very rich, mainly fish, shrimp, frogs, shellfish, loach, chicken and duck embryos, mutton, beef, rabbit meat, earthworms, etc. For artificial compound feed, eel compound feed can be selected; we have already developed artificial compound feed for the giant salamander. The feed coefficient for raising adults on natural feed is 3.5 to 6.3. The feed coefficient for raising adults on artificial compound feed is 2.8 to 3.6. Each place can decide the feed varieties to use according to local feed resource conditions.

(2) Feeding: In order to improve the farming efficiency of the giant salamander and reduce feed costs, before feeding it is necessary to understand the adult's ability to digest, absorb, and utilize the nutrients in the feed so as to determine reasonable feeding. Reasonable feeding includes factors such as the giant salamander's nutrition, growth, metabolism, physiology, and ecological environment, as well as feeding amount, feeding frequency, feeding methods, and feeding principles.

* Feeding time and frequency: Under suitable temperature conditions, the giant salamander has strong digestion and absorption; generally feed once every 2 to 3 days, and if the humidity is below 10°C, feed once every 5 to 7 days. The giant salamander hides by day and emerges at night, feeding at night; therefore, in summer the feeding time is from 8 to 10 p.m. each day, and in winter it can be from 6 to 8 p.m.

* Feeding amount: There are many factors affecting the giant salamander's feeding, such as water temperature, dissolved oxygen, water quality, disease, feed variety, feed quality, etc. The amount of feed needed by the giant salamander can be calculated based on the number of adults in the pond and the daily feeding rate; the calculation formula is:

A＝W×E

A: Daily feeding amount;

W: Giant salamander body weight;

E: Feeding rate.

Water temperature is an important factor affecting the giant salamander's feeding, because the giant salamander is a poikilothermic animal, and its body's physiological metabolism changes with the water temperature. Within the suitable temperature range, the giant salamander's feeding and growth are positively correlated with rising water temperature. Generally, feeding and growth occur above 12°C, with the largest feeding amount and fastest growth at 18 to 23°C; when the water temperature rises above 26°C, the feeding amount decreases, and above 28°C it enters "summer dormancy." Under suitable temperature and the same feed quality conditions, dissolved oxygen and water quality play the main role. Therefore, the feeding amount for adults must be determined by integrating various factors. After 10 years of research results, we have obtained a feeding standard under different water temperature conditions, which can be used for feeding in adult farming.

* Feeding method: Feeding must be determined according to the giant salamander's biological and ecological habits to establish a reasonable feeding method. In order to improve feed utilization and reduce feed costs, feeding must adhere to the four-fixed feeding method, namely fixed time, fixed location, fixed quality, and fixed quantity.

(1) Fixed time: Feed on time according to the giant salamander's biological habit of feeding at night, and also appropriately advance or delay according to season, water temperature, and water quality conditions. The general feeding time: in summer, set it at 10 p.m.; in winter, at 8 p.m.

(2) Fixed location: Cultivate the giant salamander's habit of feeding at a fixed location, which can promote concentrated feeding. Feeding in groups not only improves the giant salamander's appetite and increases food intake, but also reduces feed scattering and improves feed efficiency.

(3) Fixed quality: If artificial compound feed is used, it should be stored in a low-temperature, dry place away from moisture. Because adult farming purposes differ, the feed additives added also differ. In order to improve the utilization rate of protein in compound feed, oil and fat should be added during feed preparation; generally fish oil, vegetable oil, etc. are required. The amount of oil and fat added increases or decreases with water temperature; generally when the water temperature is 18 to 23°C, add 5% each of fish oil and corn oil; when the water temperature is 14 to 1.7°C, the amount of oil and fat added is 5% to 6%; when below 12°C, oil and fat may not be added. Natural feed must be fresh and clean, and spoiled feed must never be fed. Ideal natural feeds are loach, earthworms, crucian carp, and chicken and duck embryos.

(4) Fixed quantity: According to different factors such as the giant salamander's feeding and digestion, individual growth, individual size, water temperature, and water quality, feed an appropriate amount of feed.

Farming Management

1. Management of the adult pond: After a period of farming, adults grow in size and density relatively increases, and giant salamander diseases also occur accordingly; therefore, daily management work is very important. The daily management of the adult pond can be summarized as one diligence, two earlies, three observations, and four preventions.

One diligence: That is, frequent pond patrols. Patrol the pond 3 times a day: patrol in the morning to observe conditions after feeding, patrol at noon to watch for water temperature changes, and patrol in the evening to observe adult feeding conditions.

Two earlies: That is, early stocking and early feeding. Pay attention to whether the giant salamander is feeding when the water temperature rises after the Spring Festival; if it is not feeding, use heating to make the adults feed as early as possible.

Three observations: That is, observe feeding, observe whether there is food grabbing or spitting, and observe water quality. Observing feeding mainly means observing whether the adults feed in a concentrated or scattered manner at the feeding site. Observe whether there is food grabbing or spitting so as to adjust the feeding amount. Observing water quality mainly means observing whether the water quality is fresh and whether transparency is high, so as to take measures to improve water quality.

Four preventions: That is, prevent heatstroke, prevent disease, prevent escape, and prevent water deterioration.

(1) Preventing heatstroke is one of the important tasks in adult pond management in summer. Because summer water temperature is high, adults easily die; therefore, measures must be taken to prevent heatstroke and lower temperature, which is beneficial to giant salamander growth. Outdoor heatstroke prevention mainly involves installing shade materials to reduce light intensity. Water changes should be carried out late at night, which is beneficial for adults to "pass the summer."

(2) Preventing disease means preventing giant salamander diseases. Always pay attention to the giant salamander's feeding and activity conditions. If an adult is found swimming alone away from the group, inspect and study the condition, adopt isolation and prevention measures, and treat it in time.

(3) Preventing escape means preventing adults from escaping. Frequently check the inlet and outlet areas, strengthen management, and prevent escape.

(4) Preventing water deterioration means preventing water quality from deteriorating.

In addition to feed management, the adult pond also requires water quality management and prevention and control of adult diseases.

2. Water quality management: The adult pond requires fresh water quality, low amounts of zooplankton and harmful organisms, and a transparency of 50 to 60 cm. The water quality of the adult pond will directly affect the giant salamander's feeding and the occurrence of giant salamander diseases. When water quality is good, adults have strong feeding ability, are robust, and have fewer diseases.

(1) Water change: The self-purification capacity of adult pond water is poor, so the pond water must be changed frequently. Generally, the daily water change amount is 2/3. In summer high temperatures and when water quality deteriorates, the pond water should be drained completely and then refilled with new water.

(2) Do a good job of keeping the pond water clean: During daily management, promptly remove residual feed, debris, and dead giant salamanders floating on the water surface. Keep the pond water clean and prevent water quality from being polluted by the decomposition of such substances.

(3) Pay attention to changes in plankton and harmful organisms in the pond water: The massive reproduction of plankton is one of the main factors causing water quality changes in the adult pond and disease in adults. Once a large amount of plankton is found in the pond water, handle it promptly and carry out disinfection.

3. Disease prevention and control: The occurrence of giant salamander diseases will directly affect adult feeding, survival rate, and yield. Disease prevention and control for giant salamanders must adhere to the principle of prevention being more important than treatment. Disease prevention and control for giant salamanders also requires doing the following work well.

(1) For adult water, tap water or underground well water is best, to reduce bacteria and pollution sources. For farms using natural water sources such as reservoirs, mountain stream springs, and shaded river water, the inlet water must be filtered to prevent harmful organisms from entering the adult pond.

(2) Do not polyculture fish and shrimp carrying pathogens in the adult pond.

(3) Newly introduced giant salamanders for the adult site must be disinfected before being placed in the pond for farming.

(4) Regularly disinfect the pond water, and feed medicated bait or carry out medicated baths to prevent disease occurrence.

Separate Farming of Adults

After a period of farming, due to differences in feeding, digestion, and absorption, the differences in adult size become obvious, and such differences will gradually intensify. This is because large-size adults have high feeding intensity. With a large feeding amount, they grow quickly; while small-size adults have poor food-grabbing ability and eat less, so their growth gradually slows. Thus, giant salamanders in the same adult pond become differentiated into large, medium, and small individuals. In order to avoid the weak being preyed upon by the strong, adults must be graded and raised in separate ponds.

1. Preparation before separate farming

(1) Giant salamander ponds and tools: Before separate farming, prepare the giant salamander ponds and tools for separate farming. The giant salamander ponds should first be disinfected and the water quality cultivated. For the method, see the stocking section. Tools for separate farming of adults include plastic buckets and plastic basins.

(2) Stopping feeding: Adults should stop feeding for 5 to 7 days before separate farming, which can prevent injuries caused during catching.

2. Catching: Drain the prepared adult pond for separate farming, then scoop up adults of various sizes that are ready for separate farming, place them in previously prepared plastic basins, and finally put them into their respective new adult sites.

3. Several issues in separate farming of adults

(1) The giant salamander is a light-fearing animal, so separate farming should be carried out on cloudy and rainy days. On cloudy and rainy days, the temperature is lower and the air humidity is high, so adults are not easily injured during catching. In summer, when the temperature is high and light intensity is strong, separate farming should be carried out late at night; never carry out catching and separate farming operations under direct sunlight.

(2) The water temperature of the giant salamander ponds for separate farming should be basically the same. If the water temperatures of the two ponds differ greatly, it is easy to cause adults to regurgitate and develop diseases. Therefore, the water temperature of the adult ponds for separate farming is required to be close, so that the giant salamander will not refuse to eat.