The objective of this study was to document the frequency of occurrence of very rare fish species as well as to note the changes in diversity over time. Fish species recorded fewer than five times over the past 40 years (1969-2008) from the coasts of Izmir (central Aegean Sea) were included in the account and considered as being very rare. The records are listed chronologically. Fish species recently recorded in the area for the first time are also included. Changes in qualitative and quantitative composition of the ichthyofauna along the coasts of Izmir are also discussed.