In present study, the different fishery biology data including sex composition, age, length and weight distributions, age-length, age-weight and length-weight relationships, condition factor of Danube bleak, Alburnus chalcoides, which has the economical value and inhabiting Todurge Lake, were investigated. A total of 560 samples were captured with monthly periods between April-November 1997. Sex ratio (male-female) of population which consisting of seven age classes (I-VII) was calculated as 1: 0.25. Dominant age group in the population was III with 65.2%. Minimum and maximum fork length and body weight values were ranged between 86 mm and 262 mm, 6.0 g and 219.8 g, respectively. Mean fork length changed between 102.2 and 252.0 mm, and body weight was between 10.13 and 213.45 g. Mean fork length of females was longer than length of males in all age groups (except for V age). The smallest prey size was determined as 200 mm (total length). Length-weight equation was W=0.0054 L3.2690 for all individuals (r(2)=0.90). Mean condition factor in the population changed between 0.92 and 1.34. It is considered that the fish over IV age should be catched in order to sustain and protect the population. In this context, amount of the fishable stock was constituted 14% portion of the population.