Detailed Explanation of Key Technical Points for Disease Prevention and Control in Soft-Shelled Turtles

In zoological classification, the soft-shelled turtle belongs to the phylum Vertebrata, class Reptilia, order Testudines, family Trionychidae, genus Pelodiscus. It has strong adaptability to the external environment and great vitality, and is distributed across temperate and subtropical regions worldwide, as well as commonly found throughout China.

The soft-shelled turtle is an amphibian that breathes with its lungs, mainly living in water, occasionally coming ashore to rest, or swimming to the water's surface with its head extended above the water to breathe.

The ecological habits of the soft-shelled turtle are characterized by three likes and three fears. First, it likes quiet and fears disturbance; second, it likes sunlight and fears wind; third, it likes cleanliness and fears dirt.

The soft-shelled turtle is naturally timid but combative. Large turtles killing small ones and strong turtles eating weak ones occur frequently. During the reproductive season, when male and female turtles mate, fights break out among male turtles, causing many turtle deaths.

The soft-shelled turtle also has the ability to dig burrows and climb, so when building turtle ponds, installing effective escape-prevention facilities is very important.

The soft-shelled turtle has a broad and omnivorous diet and is rather voracious, primarily feeding on animal-based feed with high protein content. Types of animal-based feed include snail and clam meat, mussel meat, fish meat and @#@237@#@, etc. Aquatic insects are also a favored bait for soft-shelled turtles, and they especially love eating animal viscera and offal from livestock and poultry processing plants. Plant-based feed includes cooked sorghum, corn, melon rinds and fresh tender aquatic plants.

The soft-shelled turtle grows slowly. Under natural conditions, the farming cycle for soft-shelled turtles is three to four years, but when farmed under warm water conditions, the growth rate can be greatly accelerated, reaching over 500 grams in just over one year of farming.

Because soft-shelled turtles command a high market price and turtle farming yields relatively high economic returns, turtle farming has been widely developed in many places across the country and has reached a certain scale. At the same time, large-scale artificial turtle farming inevitably increases turtle diseases. The following introduces disease prevention and control techniques for soft-shelled turtles.

Prevention of Soft-Shelled Turtle Diseases

Soft-shelled turtles have strong vitality and disease resistance, and diseases rarely occur during the rearing process. However, poor rearing practices can also cause turtle diseases, and even mass mortality, so preventive measures must be taken. For the prevention of turtle diseases, the following tasks should mainly be carried out:

(1) The water quality of turtle ponds should be fresh and clear, appearing brownish-green. If ammonia-containing water flows in, it will immediately cause parotitis disease. This disease spreads very quickly. When a small number of turtles are infected, if they are not isolated and treated promptly, the entire pond faces the danger of being wiped out. During the farming process, new water should be regularly added to keep the water quality lively and fresh, and strictly prevent deterioration into black and smelly water. This is especially important for rearing hatchling and juvenile turtles.

(2) The feed for turtles should be fresh in quality and sufficient in quantity. If the feeding amount is insufficient, it will cause competition for food and the phenomenon of the strong overpowering the weak. If feeding is uneven, turtles will be in a state of alternating hunger and satiety, which is detrimental to normal growth and reduces resistance to diseases. Rotten and spoiled feed will further cause infectious diseases. Therefore, when feeding, one must conscientiously follow the principles of fixed time, fixed quantity, fixed location and fixed quality.

(3) Preventive measures should be taken against natural enemies of hatchling and juvenile turtles.

(4) During the overwintering period, antifreeze measures should be taken. When overwintering in greenhouses, avoid sudden temperature fluctuations; when transferring between ponds, prevent turtle injuries, and turtles that are injured or suffering from diseases should be reared in separate ponds; in the hot midsummer, when pond water temperature is too high, cooling measures should be taken.

(5) Reasonable stocking density. Prevent excessively high farming density, or rearing strong and weak, large and small turtles in the same pond, otherwise it will cause the phenomenon of the weak being preyed upon by the strong, resulting in many injured, disabled and weak turtles, which are also highly susceptible to disease infection.

(6) When turtle disease infection is detected, diseased turtles, the pond water and their habitat sites should be promptly disinfected.

Diseases of Soft-Shelled Turtles and Their Prevention and Treatment

I. Common Turtle Diseases and Prevention and Treatment Methods

1. Hemorrhagic Disease

Caused by a virus. Diseased turtles develop bleeding spots and bleeding points all over the plastron, ulcerative growths on the carapace with bleeding ulcers, massive bleeding and severe necrosis of the pharyngeal inner wall, and bleeding symptoms may also appear in the intestines, kidneys and liver. Prevention and treatment methods: (1) Pay attention to isolating and rearing diseased turtles, and use quicklime to clear and disinfect the pond; (2) Use sulfa drugs or antibiotics mixed into feed for feeding, with a daily dose of 0.1 mg per kilogram of body weight showing certain efficacy.

2. Saprolegniasis

Caused by massive proliferation of water molds, it is relatively harmful to hatchling and juvenile turtles. The fungal bodies often parasitize the limbs, neck and underside of the turtle, forming cotton-like masses. Diseased turtles have poor appetite and slow growth. Prevention and treatment methods: (1) Handle turtles carefully during stocking, harvesting and transportation to avoid skin injuries; (2) Use 2 ppm malachite green for whole-pond disinfection, or use a mixture of 0.4‰ baking soda and 0.4‰ table salt sprinkled over the entire pond, which has a certain preventive effect; (3) Diseased turtles can be bathed in 3-4% salt water for 5 minutes.

3. Big Neck Disease

Also known as branchial gland inflammation, it is a bacterial disease that spreads rapidly with an extremely high mortality rate. Diseased turtles have noticeably swollen necks, bleeding from the mouth and nose, and generalized edema, but no bleeding points on the abdomen. The middle of the abdomen appears whitish, showing an anemic appearance. In severe cases, there is massive bleeding in the intestines, which become filled with congested blood. Prevention and treatment methods: Remove diseased turtles for isolation; pond water, bottom sand, rearing tools and feeding utensils must be disinfected with 200 ppm bleaching powder before use.

4. Bell Animalcule Disease

A disease caused by parasitism of bell animalcules. Diseased turtles show reduced feeding rates, with clusters of cotton-like masses appearing on the limbs, shell, neck and other areas. When the water is green, the parasite bodies also become green. Treatment methods: Bathe in 10 ppm bleaching powder aqueous solution for 24 hours, or soak in 2-3% salt water for 3-10 minutes, which also has good results.

5. Skin Rot Disease

This is caused by bacterial infection of wounds sustained from fighting in the pond. Bacterial toxins cause necrosis of the skin and tissue surrounding the wounded area. The main symptoms are ulceration and necrosis at the limbs, neck, tail or shell edges. When the limbs ulcerate, the claws may also fall off, exposing the bones; when the neck is affected, muscles and bones are exposed. For the prevention and treatment of skin rot disease, attention should first be paid to pond water cleanliness. When turtle disease is detected, prompt isolation and treatment should be carried out. Diseased turtles can be soaked in 10 ppm sulfa drugs or antibiotic solutions for 48 hours.

6. White Spot Disease

White spot disease, also known as mucormycosis, is prone to occur in flowing-water turtle farming. The main symptom is the appearance of white spots on the limbs, skirt edges and other areas of diseased turtles. In the early stage, it appears only at the edges, then gradually expands to form patches of blood spots, causing epidermal necrosis and decay. Generally, the mortality rate of this disease is relatively low, but when the mold parasitizes the pharynx, it affects breathing and gradually leads to death. This disease can occur year-round. The prevention and treatment methods for this disease are thorough pond clearing and disinfection before stocking, and careful handling during stocking operations to prevent turtle injuries. After injury, 1% malachite green ointment or sulfa ointment can be applied to the affected areas; soaking diseased turtles in 10 ppm bleaching powder aqueous solution for 3-5 hours can also effectively treat this disease. The pathogen of white spot disease is a type of mold. In the fresh water of flowing-water ponds, it tends to reproduce faster, while in sewage water bodies, the reproduction and growth of this mold is inhibited by other competing bacteria. Therefore, antibiotic drugs may have the effect of promoting the development of this disease, so they are generally not used; whereas in turtle ponds that are regularly fertilized, maintaining a certain degree of water fertility has a certain effect on controlling this disease.

7. Feed-Related Disease

Caused by feed spoilage leading to massive accumulation of denatured fatty acids in the body, resulting in metabolic dysfunction and pathological changes. Diseased turtles have elevated and raised bodies, becoming heavy and thick, with a dark brown plastron bearing dense grayish-green markings, swollen limbs and neck, subcutaneous edema, and abnormal posture. Diseased turtle fat changes color, appearing loess-colored or yellowish-brown with a foul odor. Prevention and treatment methods: Feed fresh, high-quality feed, and regularly add vitamin E to the feed. If artificial compound feed is used, this disease is less likely to occur.

8. Turtle Disease Caused by Poor Water Quality

The cause is that when pond water is not circulating, water quality deteriorates, and ammonia nitrogen content in water remains above 100 ppm for a long time, this disease is prone to occur. Diseased turtles show obvious congestion, redness, swelling and ulceration of the limbs and abdomen, exposing the abdominal bone plates, and the skirt edges ulcerate into a sawtooth shape or develop many lumps. Prevention and treatment methods: Regularly maintain fresh pond water. If this disease is detected, promptly changing the pond water can lead to recovery.

9. Red Plastron Disease

May be caused by bacterial invasion. The plastron develops redness, swelling and even decay, exposing the abdominal bone plates; diseased turtles have enlarged necks, refuse food, respond slowly, often burrow into grass, and are very easy to catch. (1) Soak or apply 1 ppm malachite green. (2) Intramuscular injection of gentamicin at a dose of 15,000 units per kilogram of turtle.

II. Natural Enemies of Soft-Shelled Turtles and Their Prevention and Control

The main natural enemies of soft-shelled turtles are mosquitoes, rats, ants, cats, yellow weasels, hawks, etc. These natural enemies are most harmful to turtle eggs and hatchling turtles. Snakes will dig into egg burrows and swallow turtle eggs and hatchling turtles; wild rats like to dig burrows in turtle nesting grounds, causing turtle eggs to dry out and die; ants often swarm and attack hatchling turtles; cats and yellow weasels are even more harmful to hatchling turtles, because soft-shelled turtles secrete a special fishy-smelling liquid that is easily detected by cats and others, and cats and yellow weasels are habituated to nocturnal activity, which is precisely when soft-shelled turtles are active. In addition, otters can dive underwater and harm turtles. To prevent natural enemy damage, first reinforce pond dikes or walls, plug holes and cracks, and cut off channels and hiding places for natural enemies to enter the pond. For ants, in addition to immediately exterminating ants found in the nesting ground, pesticides can also be scattered around the nesting ground to prevent ant colonies from entering. Metal nets can be set above turtle ponds to prevent bird and animal damage.