Gender relationships between total length (LT) and standard length (LS) (mm) were compared to weight (MB)(mg) in the round goby, Neogobius melanostomus, for tributary and harbor embayment habitat in southern Lake Michigan. Length and weight relationship (n = 413), LT length-frequency distribution, and sex ratios were determined. A strong positive correlation (P>0.001) was found between length (LT and LS) and weight for both males and females. Male populations showed positive allometric growth rates with b-values and Fulton Condition indices above 3.0, females populations showed positive allometric growth in the tributary populations, but a negative allometric growth rate in the harbor population.