The Aegean gudgeon Gobio bulgaricus (Drensky, 1926) is a freshwater fish species restricted to the western parts (Thrace) of Turkey. The aim of the present study is investigating key parameters such as age, growth, reproduction and feeding habits of G. bulgaricus in the Istranca Stream to determine biological characteristics of the species. During monthly samplings from March 2012 to June 2013, G. bulgaricus specimens were collected from the endorheic Istranca Stream, which is draining to the Lake Durusu in Istanbul. The results showed that the lifespan of the species was 5 years. The length-weight relationships of G. bulgaricus indicated positive allometric growth and the relationship was lnW=-3.976+3.080lnSL for females, lnW=-4.008+3.088lnSL for males and lnW=-4.049+3.118lnSL for all individuals. The mean size at first sexual maturity (L-m) was 4.03 cm SL for females and 3.94 cm SL for males. Absolute fecundity ranged from 355 to 5556 eggs with mean of 1179 +/- 152 eggs. Prey analyses of digestive tract content indicated that G. bulgaricus was largely omnivorous (more precisely insectivorous) feeding mainly on aquatic insects and a small amount of plant and animal materials. Diptera larvae (IRI%=96.49) were the dominant prey of G. bulgaricus in terms of index of relative importance. It is considered that the present results will increase our knowledge of the life-history traits and feeding of G. bulgaricus.