Prevention and Control Methods and Technical Key Points for Rotting Stomach Disease in Sea Cucumber Aquaculture

This disease mostly occurs in the late auricularia larval stage, and is more likely to break out during the high-temperature period from June to July each year and when larval rearing density is high. The disease has been found in both Shandong and Liaoning provinces, and its incidence rate has shown a trend of increasing year by year. The main symptoms of disease and death are: the larval stomach wall thickens and becomes rough, the surrounding boundary of the stomach becomes blurred, then shrinks, becomes smaller and deformed; in severe cases the entire stomach wall becomes eroded, ultimately leading to larval death. Diseased larvae show reduced feeding ability or stop feeding, retarded development, uneven morphology and size, and a low metamorphosis rate from auricularia larva to doliolaria larva.

The causes of the disease are, on the one hand, poor-quality feed such as aged, settled and deteriorated unicellular algal feed, or feed with a single nutrient source such as feeding only chrysophytes, Platymonas and similar feeds. On the other hand, infection of larvae by some bacteria can also cause this disease. The author has now isolated 2 strains of pathogenic bacteria, and their taxonomic identification is ongoing.

There are two main prevention and control measures: on the one hand, feed fresh and suitable feed such as Chaetoceros, Dunaliella or marine yeast to meet the needs of larval development and growth; on the other hand, appropriately increase the water exchange volume to reduce the number of bacteria in the water body, and use furan-type antibiotics at 3×l0-6 to 5×10—6 for medicated bathing in combination, which has a good curative effect.