Reproductive Biology of King Nase in Beheshtabad River in Chaharmahal and Bakhtiari

Aims: King Nase fish (Chondrostoma regium) is a benthopelagic species that lives in stagnant and current water with a temperature range of 3-21°C and in the middle and upper parts of the river. The aim of this study was to evaluate the reproductive characteristics of King Nase fish.
In this experimental study, 335 fish were randomly caught and transferred to the laboratory after anesthetization and fixation for biometric measurements and dissections. The data were analyzed by one-way analysis of variance (ANOVA), Duncan's multiple range test (MRT), and unpaired T-test and SPSS 19 software.
Findings: The fork length and weight changes in male and female fish in all age groups, except for 1 and 2 year in females, showed a significant difference. There was a significant correlation between fork length, weight, and age of fish with its fecundity (r2=0.6922; r2=0.6852; r2=0.7284). Age groups of the males and females were 1 to 5 and 1 to 6 years, respectively. The sex ratio of male to female was 1:1.3. The oocyte diameter significantly increased from April to June and decreased in July and August. Changes in oocyte diameter corresponded to gonadosomatic index. The highest gonadosomatic index in males and females was in April and June, respectively, and varied with other months (p The spawning season of King Nase fish is from late March to June and has a group simultaneous spawning pattern.