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.