The present work is aimed at determinig the fish fauna of the Gönen Stream. Fort his purpose, four different seasonal field studies were performed during 2010 and 2011. Fish samples were collected from 13 stations located betwen spring and downstream by electrofishing. 14 taxon belonging to the Salmonidae, Cyprinidae, Cobitidae, Siluridae ve Gobiidae families (Alburnus chalcoides, Barbus oligolepis, Cyprinus carpio, Carassius gibelio, Phoxinus phoxinus, Pseu-dorasbora parva, Rhodeus amarus, Rutilus rutilus, Squalius cii, Vimba vimba, Cobitis fahirae, Salmo trutta, Silurus glanis, Neogobius fluviatilis) in Salmonidae, Cyprinidae, Cobitidae, Silu-ridae and Gobiidae families were determined in the stream. Carassius gibelio, Cyprinus carpio, Pseudorasbora parva, Rutilus rutilus, Silurus glanis species were reported at the first time in the Gönen Stream by this study. As a result of this research, it was stated that the most abun-dant fish diversity belonged to the dam lake which is located in the centre of the river and sluices of regulator, and the dominancy of the fish groups belonged to Cyprinidae familia with ten species.