Morphometric relationships of African big barb, Labeobarbus intermedius (Rüppell, 1836) (Pisces: Cyprinidae) in Lake Koka, Ethiopia was studied based on the total number of 266 adult fish samples collected in April-May and July-August 2011. Fish ranging from 23.3 to 49.0 cm in total length (35±4.1 cm) and from 95.4 to 1200 g in total weight (434.4±206.5 g) were randomly sampled. Of these, 55.6% (n=148) were males and 44.4% (n=118) were females. The length-weight relationship of the males, females and combined fish were curvilinear and statistically significant (P< 0.01). L. intermedius in Lake Koka has positive allometric growth pattern, which was statistically significant (p< 0.01). Females were more allometric in their growth pattern, but statistically not significant (P>0.01). Length-length relationships between total length (TL) and fork length (FL), fork length (FL) and standard length (SL), TL and SL were linear and statistically significant (P<0.01). Result of Fulton condition factor showed no significant differences between males and females (P>0.01). The overall condition factor for all sampling period was 1.0.
Key words: Allometric growth, Labeobarbus intermedius, condition factor, Lake Koka, length-weight relationship.