Biometric and condition factor analysis of freshwater crabs from River Burhi Gandak, Bihar

The current investigation was carried out from August 2022 to July 2023 at river Burhi Gandak, Bihar (India). This investigation involved a description of crab species found in the study area, morphometric measurements, length-weight & length-length relationship and condition factor. In this study, we studied one crab species of family Gecarcinucidae viz, S. tribolata, and one species of family Potamidae, Acanthopotamon martensi. The mean values of biometric parameters of S. tribolata like carapace width (CW) were 34.65±7.83, 40.10±8.17, and 37.23±8.43 mm for male, female, and combined respectively, while in Acanthopotamon martensi it is 26.26±3.74, 25.91±4.73 and 26.39±4.63 mm for male, female and combined respectively. In carapace width-total weight relationship analysis we found that the exponent ‘b’ value was 2.83 and 3.03 for S. tribolata, and A. martensi respectively, which coincide with isometric growth. Condition factor analysis revealed sex-specific variations in both crab species. S. tribolata females exhibited higher mean Fulton's and modified condition factors than males, while A. martensi males showed slightly higher values. Relative condition factors for both species were close to 1, indicating a general state of good condition with minor deviations from expected weight for length.