How to prevent and treat luminous bacterial disease in white shrimp (Penaeus vannamei) larvae
Prevention and treatment of luminous bacterial disease in white shrimp (Penaeus vannamei) larvae
Prevention and treatment of luminous bacterial disease in white shrimp (Penaeus vannamei) larvae
Luminous bacteria are one of the most serious diseases in nursery production. It occurs from the zoea stage to the postlarval stage, and is most commonly seen in mysid and postlarval stages. It comes on quickly and causes high mortality, posing a serious threat to nursery work.
Symptoms: In the early stage of the disease, the larvae's activity decreases, and they are often found in the middle and lower layers of the water; mysids and postlarvae have weak flicking ability, poor phototaxis, and reduced or no feeding; the body turns white, especially the cephalothorax, which becomes milky white. Dying or dead larvae emit fluorescence in the dark; the brightness of the fluorescence varies with the severity of the disease and the size of the larvae. Generally, no fluorescence is visible in the early stage of the disease; when the larvae are in a dying state, weak fluorescence can be seen; after the larvae die, the fluorescence emitted is strongest and can last for more than ten hours, and it is no longer visible only after the carcass decomposes.
Cause: The route of infection is unpresettled seawater; after it is taken into the nursery pond and heated, the number of Vibrio increases sharply. The deposition of feces and leftover bait in the nursery pond, with its high organic matter content, provides good nutritional conditions for the growth and reproduction of Vibrio. Abnormal conditions in the nursery environment, such as the quality of the larvae, excessive density of larvae stocked in the pond, and large differences in water physicochemical factors, can all lead to infection by luminous bacteria.
Treatment methods: 1. Splash norfloxacin over the whole pond so that the water contains 2 ppm norfloxacin, using it 3 times in succession. 2. Splash compound sulfamethoxazole over the whole pond so that the water contains 2.5 ppm compound sulfamethoxazole, using it 3 times in succession.
Luminous bacteria are one of the most serious diseases in nursery production. It occurs from the zoea stage to the postlarval stage, and is most commonly seen in mysid and postlarval stages. It comes on quickly and causes high mortality, posing a serious threat to nursery work.
Symptoms: In the early stage of the disease, the larvae's activity decreases, and they are often found in the middle and lower layers of the water; mysids and postlarvae have weak flicking ability, poor phototaxis, and reduced or no feeding; the body turns white, especially the cephalothorax, which becomes milky white. Dying or dead larvae emit fluorescence in the dark; the brightness of the fluorescence varies with the severity of the disease and the size of the larvae. Generally, no fluorescence is visible in the early stage of the disease; when the larvae are in a dying state, weak fluorescence can be seen; after the larvae die, the fluorescence emitted is strongest and can last for more than ten hours, and it is no longer visible only after the carcass decomposes.
Cause: The route of infection is unpresettled seawater; after it is taken into the nursery pond and heated, the number of Vibrio increases sharply. The deposition of feces and leftover bait in the nursery pond, with its high organic matter content, provides good nutritional conditions for the growth and reproduction of Vibrio. Abnormal conditions in the nursery environment, such as the quality of the larvae, excessive density of larvae stocked in the pond, and large differences in water physicochemical factors, can all lead to infection by luminous bacteria.
Treatment methods: 1. Splash norfloxacin over the whole pond so that the water contains 2 ppm norfloxacin, using it 3 times in succession. 2. Splash compound sulfamethoxazole over the whole pond so that the water contains 2.5 ppm compound sulfamethoxazole, using it 3 times in succession.