Age and growth of Isfahan tooth-carp, Esmaeilius isfahanensis (Hrbek, Keivany & Coad, 2006) in the Zayandehrud River, Central Iran

Age and growth of the Isfahan tooth-carp, Esmaeilius isfahanensis, was studied in the Zayandehrud River, in central Iran, from June 2016 to May 2017. Among the 485 specimens, age groups in both sexes ranged from 0+to 2+. The overall sex ratiowas 1M:1.2F. Maximum total length and weight were 44.9mm and 1.6g for males and 53.6mm and 2.4g for females. The Minimum total length and weight was 26.8mm and 0.40g for males and 32.0 mm and 0.5g for females. The most frequent age groups were 1+in bothsexes. The highest value for the condition factor was observed in July. The von Bertalanffy growth parameters of E. isfahanensis were estimated as k= 0.36, L∞= 34.98mm, t0=1.10 for males and k= 0.53, L∞= 41.02mm and t0= 0.14 years for females. The length-weigh relationship was described as W= 0.00005L2.84 (r2= 0.84) for males and as W= 0.00005L2.84 (r2= 0.83) for females, indicating an isometric growth pattern in both sexes. The Growth performance index φ` was estimated as 6.08 for males and as 6.79 for females, indicating a faster growth rate in females.