Fish lice (Argulidae: <i>Argulus</i> spp.) infestations detected on freshwater fish in Türkiye: <i>Argulus foliaceus</i> (Linnaeus, 1758) and <i>Argulus japonicus</i> Thiele, 1900

Abstract Argulus (Crustacea: Branchiura) species, also known as fish lice, are among the most important aquatic ectoparasites infesting fish in Türkiye and worldwide because of their low host specificity and widespread distribution. Approximately 130 species have been identified within this genus, which inhabit freshwater, marine, and estuarine environments. To date, only two species have been reported from Türkiye: Argulus foliaceus (Linnaeus, 1758) and A. japonicus Thiele, 1900. This study aimed to determine the host diversity of Argulus species reported in Türkiye through a literature review. Additionally, we aimed to report A. japonicus infestations detected in common carp ( Cyprinus carpio L.) and Amur carp ( Cyprinus rubrofuscus LacepPde) (ornamental form; koi) during routine parasitological surveys conducted at the Mediterranean Fisheries Research, Production, and Training Institute (Antalya, Türkiye). Argulus japonicus , a parasite found on common carp ( C. carpio ), represents a new host–parasite association for the parasitic fauna of Türkiye.