An Investigation on the age and growth of Dwarf snakehead fish Channa gachua (Hamilton, 1822) from Sarbaz River in Sistan and Baluchistan Province, South-eastern Iran

The present study investigated age and growth patterns of the Dwarf snakehead Channagachua from Sarbaz River. A year round regular monthly collection of this species was carried out from June 2013 to May 2014 (Except in August). The specimens total length and total weight ranged from 13 to 153 millimeters, and 0.04 to 49.49 grams respectively. Sex ratio was 1: 1.23 in favor of males. Length–weight relationship was calculated as W = 0.0089TL 3.11 (r2= 0.99) for males and W = 0.0079TL 3.16 (r2=0.99) for females and for the entire Sexes combined as W = 0.0103TL 3.04 (r2=0.99) being all metrically positive for both sexes. Age determination by opercula readings revealed that the majority of specimens belonged to the age group of 3+, with 6+ being the oldest age recorded for both sexes. The von Bertalanffy growth model was estimated as Lt =21.78[1- exp-0.16(t + 3.62)] for males,Lt =25.40[1-exp-0.13(t + 0.32)] for females and Lt =26.44 [1-exp- 0.12(t + 3.72)] for the whole Sexes combined. The highest values of condition factor were obtained in December and April for both sexes. The results indicated that biological factors such as growth and sex ratio in Dwarf Snakehead species from Sarbaz River show considerable differences compared to the specimens from other localities of its natural habitats.