We examined 283 wild Takifugu xanthopterus samples from the East China Sea to investigate the infection of Anisakis. It was found that the infection of Anisakis in T. xanthopterus was the highest in November. In situ photographing of the infected tissue of T. xanthopterus showed that the highest infection rate was as high as 60% in the liver and average infection intensity in the liver is 3 anisakises per fish. Identification by mitochondrial DNA molecules and morphologic features, the parasite of T. xanthopterus is Anisakis pegreffii. LC-MS/MS showed that the content of TTX in Anisakis was 425 ng/g. This is the first time that an anomalous nematode parasitic in T. xanthopterus has been found to have a tetrodotoxin.