This study reports the first recorded instance of Atherina boyeri (Risso, 1810) in the Bayramiç Reservoir, located on the Karamenderes Stream. Since 2005, ichthyological researches have been carried out in the Bayramiç Reservoir by various researchers, but none of them have noted the existence of A. boyeri in this reservoir. In the field studies conducted between May 2016 and July 2017, a total of 98 A. boyeri specimens was caught. In these samplings, a 70 m long and 2 m wide beach seine net with 10 mm a mesh size was used. Although a small number of A. boyeri was caught during the first observation in October 2016, more individuals were observed in July 2017. The fork length of the A. boyeri observed was between 2.7-8.8 cm and the weight ranged between 0.06-4.31 g. The bimodal length distribution of the specimens indicates that there have been multiple incidents of adult specimens entering the reservoir and that these individuals have given birth to new offspring. The translocation of A. boyeri into the Bayramiç Reservoir might have been due to unauthorized introduction by fishermen or through illegal release by anglers as fish bait. However, the distribution map of A. boyeri in inland waters in Turkey shows significant overlap with the migration routes of big waterfowl. The waterfowl might partially be responsible for the spread of the adult specimens across short distances
