Distribution of Tetrodotoxin in Wild Pufferfish from the Southeastern Coastal Regions of China

Wild pufferfish are abundant in the coastal waters of southeastern China, yet systematic data on their toxicity remain limited. This study collected 1230 specimens from Fujian, Guangdong, Guangxi, and Hainan and quantified tetrodotoxin (TTX) in nine tissues (eyes, skin, muscle, ovaries/testis, liver, digestive tract, kidneys, and heart) by ELISA. In total, 10 species were identified (Lagocephalus wheeleri, L. gloveri, L. inermis, L. lunaris, Takifugu xanthopterus, T. ocellatus, T. niphobles, T. poecilonotus, T. bimaculatus, T. oblongus). All tissues of L. wheeleri and L. gloveri contained TTX below the safety limit (2.2 μg/g), whereas the remaining eight species showed varying degrees of toxicity. T. bimaculatus and T. oblongus exhibited lethal-grade toxicity, with ovarian TTX reaching 320 μg/g and 393.56 μg/g, respectively. TTX was predominantly concentrated in the ovaries, liver, skin, and digestive tract, with substantial inter-individual variation. Marked sex-dependent differences and seasonal fluctuations were observed, driven by reproductive activity, water temperature, and prey availability. This study is the first to report that the wild T. bimaculatus from this region is a highly toxic species, and confirms the lethal toxicity of T. oblongus, providing a scientific basis for managing the consumption-related risks of wild pufferfish.