Abstract: The "Yulong No.1" snakehead (Channa argus) is a new aquatic species approved by the Ministry of Agriculture and Rural Affairs of China in 2022. As the farming area increases, diseases have begun to emerge. This study aimed at the outbreak of Channa argus’ Yulong No.1’ disease in the base farm of Neijiang Academy of Agriculture and Forestry Sciences in Sichuan Province.Clinical examination, microscopic examination of parasites, bacterial isolation and culture, and PCR detection of fish viruses were performed on 10 diseased fish. The pathogen was confirmed to be Ichthyophthirius multifiliis. The results of bacteriological and virological tests were negative. The tissues were collected for paraffin section preparation and HE staining to analyze the histopathological changes. Results showed that I. multifiliis was only found in the skin and gills of fish. Histopathologically, I. multifiliis was located at the base of the gill lamella, causing the gill capillaries anemic, the respiratory epithelium swollen, and eosinophils increasing. In severe cases, the entire gill filament showed necrosis and disordered gill lamella. For the skin, I. multifiliis was limited in the epidermal layer and surrounded by flat epithelial cells; eosinophils and lymphocytes gathered in the epidermis, while the dermis and muscles were not affected. For other organs, the main histopathological changes were edema, congestion, hemorrhage, and cellular degeneration. The findings will provide a reference for the prevention and treatment of white spot disease in Channa argus "Yulong No.1" in the future.