Length-weight relationships were calculated for 48 fish species from Izmir Bay in the Aegean Sea, Turkey. A total of 3584 fish specimens were captured with beach seine, handline, fyke net, scoop net, castnet and trammel net in 2010-2014. The sample size ranged from three individuals for Squatina squatina to 140 for Mugil cephalus. R-2 values varied between 0.95 for Pomatoschistus bathi and 0.99 for Argyrosomus regius, Chelon labrosus and Mugil cephalus. All regressions were highly significant (P < 0.001). Values of the exponent b in the length-weight regression (W = aL(b)) ranged from 2.750 for S. squatina to 3.514 for Syngnathus acus and the median value was 3.134 with 25-75% of the values ranging between 3.030 and 3.218.