1. Pathogens: The primary causative agents include Aeromonas sobria, Aeromonas hydrophila, and other Gram-negative bacilli. These bacteria are commonly found in freshwater environments and can cause severe infections in various fish species. 2. Symptoms: In the early stages of the disease, yellow or yellow-white mucus is typically observed along the outer edge and caudal peduncle of the fins. As the infection progresses, redness, inflammation, and erosion appear at the caudal fin and caudal peduncle. In more severe cases, the tail fin may begin to rot, and the muscles around the tail area may become ulcerated and bleed. In extreme cases, this leads to the death of the fish. During colder water seasons, the condition often occurs as a secondary infection alongside aquatic fungi. 3. Epidemic Situation: This disease usually begins after a fish has sustained a tail injury, allowing the bacteria to enter through skin contact. It affects a wide range of freshwater fish, including eels, grass carp, tilapia, and clams, potentially causing mass mortality. While adult fish can also be affected, their mortality rate is generally lower compared to younger fish. 4. Diagnosis: Initial diagnosis is based on clinical signs and the pattern of disease spread. However, for confirmation, it is essential to isolate and identify the pathogen in laboratory conditions to ensure accurate treatment strategies. 5. Control Methods: Early intervention is crucial. Disinfectants should be applied 1 to 3 times throughout the entire pond, which can effectively control the disease in its initial stage. If the condition worsens, internal antibiotics must be administered. For every 100 kg of fish, 15 grams of Yutai No. 8 should be given twice daily (morning and afternoon) for 5 to 7 days. However, when broodstock is severely infected and loses appetite, additional measures are required. Along with disinfection, intramuscular injections of streptomycin sulfate are necessary—administering 20 ml per kilogram of fish weight. Repeated injections may be needed if the condition does not improve. If the pathogen is identified as Columnaris (a type of flexibacter), the following treatments are recommended: External Treatment: Chlorine-based disinfectants should be used to treat the entire pond system. Internal Treatments: (1) Mix 2–3 grams of compound sulfamethoxazole per kilogram of feed. Administer once in the morning and again in the afternoon for 3–5 days. (2) Add 3–4 grams of "Enteric-Fighting Spirit" per kilogram of feed. Feed twice daily for 3–6 days. (3) Incorporate 2–3 grams of sulfamethoxazole-6-dimethoxypyrimidine into the feed. Administer once daily for 4–6 days, with a double dose on the first day. It is important to follow these treatment protocols carefully to ensure effective recovery and prevent further outbreaks in the aquatic environment. ZHONGSHAN G.H.L. TRADING CO., LTD. , https://www.ghltrade.com
Diagnosis and control of freshwater fish tail disease