The differences of tetrodotoxin (TTX) levels in various parts of pufferfish (Torquigener flavimaculosus) were examined in conjunction with the seasonal and sexual variations. The TTX levels in gonads, liver, intestines, skin and muscle tissue were determined using the Q-TOF LC/MS. Instrumental analysis revealed that all examined tissues from T flavimaculosus contained high TTX concentrations. TTX levels in the gonads, liver, intestines, skin and muscle tissue of pufferfish were within the range of 5.03-100.71, 7.04-106.80, 12.59-86.30, 33.95-139.88 and 15.88-86.07 (mu/g), respectively. It was determined that in all seasons, except for summer, female individuals had higher TTX levels than males. Among all seasons, the highest level of TTX was found in winter and the lowest in autumn. Consequently, T. flavimaculosus is a highly toxic pufferfish that is dangerous for human consumption and should not be consumed under any circumstances. (C) 2018 Elsevier Ltd. All rights reserved.