short communication: some morphometric traits, condition factor, and growth indices of caridina fossarum heller, 1862 (caridea: atyidae), endemic to iran

In this paper, both of growth and size structure of a population of c. fossarum are studied for the first time. the average sizes of females were significantly higher than those in males (p<0.05). proportions of morphological characteristics to carapace length in male were significantly higher than those in females (p<0.05). no difference was detected between the ratio of rl/cl of both sexes (p>0.05). the size frequency distribution was normal for either sex, with a peak of occurrence in the size classes 5, 6 and 7 (4.0-5.5 mm). in females the growth rate of tl in relation to cl was greater than males and constant (isometric growth) in spring and summer, while in males a decreasing rate (negative allometric) in each two seasons of year was observed. therefore, as expected, the growth rate of w in relation to cl for female sex was greater in spring and summer. condition factor was higher in female shrimps (1.56) than males (1.52) (p > 0.05). on monthly based analyses, variations in the condition factor were similar for both sexes, and minimum value was observed in winter. asymptotic length (l∞), growth rate (k) and maximum life span estimated of males were 6.1 mm, 0.61 per year and 3.43 years; those for females were 6.62 mm, 0.71 per year and 3.17 years respectively.