Symptom Identification and Prevention Methods for Mold Disease in Sea Cucumber Aquaculture

April to August is the peak period for mold disease. Both juvenile and adult sea cucumbers can be affected, but this disease has not been observed during the nursery stage. No cases of mass mortality of sea cucumbers caused by mold disease have been found so far.

The typical external symptoms are edema of the body or rotting of the epidermis. Affected individuals with edema are swollen throughout the body, with thin and transparent skin, faded pigmentation, and a soft feel when touched. In individuals with rotting epidermis, the tips of the spines first turn white, then ulceration begins centered on the spines. In severe cases, the spines rot away and become white spots, after which the infected area expands, the epidermis ulcerates and sloughs off, exposing the deeper subcutaneous tissue and appearing blue-white. Although mold disease generally does not cause mass mortality of sea cucumbers, the external wounds caused by the infection can lead to secondary infection by other pathogens and a decline in appearance quality.

This disease is caused by excessive accumulation of organic matter or dead macroalgae, which leads to the growth of large amounts of mold, and the mold then infects the sea cucumbers and causes the disease to occur. At present, the author has isolated two pathogenic molds, and classification work is ongoing.

Key points for prevention and control include: (1) Prevent overfeeding and keep the pond bottom and water quality clean. (2) Avoid excessive reproduction of large green algae, and promptly remove algae that settles to the pond bottom to prevent deterioration of the pond bottom environment. (3) Take measures to clean sludge and dry the pond to prevent excessive accumulation of organic matter.