Identification of Caligus parasites infesting Morone Labrax and its impact on fish health status and pathological alteration.

Abstract

Objective: The present study was aimed to investigate sea lice infestation including morphometric, molecular identification, disease prevalence and pathological tissue alterations in wild Sea bass (Morone Labrax) naturally collected from Ezbet Elborg, Damietta province, Egypt from October 2018 to end of August 2019. Design: Descriptive study Fish: 120 wild seabass (Morone Labrax) Procedures: The collected fish from Ezbet Elborg area, Damietta province, Egypt were clinically and parasitological investigated for the prevalence of sea lice parasite with molecular identification of the collected parasite samples with study of the pathological alteration of the affected tissue. Results: The study revealed that 48 fish (40%) of the examined fish were infested with Caligus clemensi, while the higher prevalence recorded during summer season (57%) followed spring (33%), autumn (10%) and no recording during winter. The molecular identification using 18-S rDNA was done with phylogenetic analysis compared with the previously recorded caligus species on database confirming the same results of parasitology. Histopathological examination of gills, buccal cavity revealed that the gill arch contained congested blood vessels beside edema, hemorrhage and inflammatory cells infiltration due to parasitic infestation. Conclusions and clinical relevance: Caligus infestation in wild sea bass caused by Caligus clemensi lead to mortalities due to pathological tissue alterations in gills and buccal cavity.