Short Communication: Some morphometric traits, condition factor, and growth indices of Caridina fossarum Heller, ۱۸۶۲ (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<۰.۰۵). Proportions of morphological characteristics to carapace length in male were significantly higher than those in females (P<۰.۰۵). No difference was detected between the ratio of RL/CL of both sexes (P>۰.۰۵). The size frequency distribution was normal for either sex, with a peak of occurrence in the size classes ۵, ۶ and ۷ (۴.۰-۵.۵ 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 (۱.۵۶) than males (۱.۵۲) (P > ۰.۰۵). 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 ۶.۱ mm, ۰.۶۱ per year and ۳.۴۳ years; those for females were ۶.۶۲ mm, ۰.۷۱ per year and ۳.۱۷ years respectively.

Keywords:

Growth , Decapoda , freshwater shrimp , condition factor index