Prevalence and intensity of parasites in pike (Esox lucius) from Anzali Wetland and evaluation of their impacts on biometric characticties in host fish

Parasite communities of pike (Esox lucius L. 1758) were calculated  in  Anzali Wetland along with evaluating  their impacts on biometric characticties of the fish host. A total of 4338 parasites from 11 diferent species were identified including: Ichthyophthirius mutifiliis (21.88%); Trichodina sp. (8.59%); Henneguya sp. (0.78%); Tetraonchus monenteron (60.94%); Diplostomum spathaceum (23.44%); Rhipidocotyle illense (9.37%);  Posthodiplostomum cuticola (0.78%);  Raphidascaris acus (41.41%); Rhabdochona helichi (8.59%); Eustrongylides excisus (2.34%) and Lernea cyprinacea (3.13%). The occurrence of  P.cuticola in E. lucius is  reported for the first time from Anzali Wetland. By increasing total length, the average weight of the infected fish raised from 26.54 ± 12.94 g to 472.39 ± 68.38 g, the condition factor (K) from 0.64 ± 0.11 to 0.66 ± 0.06 and the gonadosomatic index (GSR) from 0.15±0.55 to 0.75±1.88. In healthy fish, the instantaneous growth rate (G) in the age groups of 1+ to 0+ years old was higher (0.617) than in the other groups, while in infected fish, the instantaneous growth factor had fluctuations in different age groups. On the other hand, the age groups of 3+ to 2+ years old had the highest growth rate (0.773). There were significant differences between the prevalence of parasites and some biometric characticties in infected fish (p<0.05).