One specimen of blunthead puffer, Sphoeroides pachygaster (Müller and Troschel, 1848) was recorded for the first time in 16 May 2020 from the Mersin Bay (NE Mediterranean, Turkey). The present paper reported the first occurrence of the blunthead puffer, S. pachygaster from the Mersin Bay (Northeastern Mediterranean). Besides, this report is the first observation for the location and fills a gap in the distribution range of the species. Some remarks on the occurrence and geographical spreading of the species in the Mediterranean Sea are given.