Confirmed Occurrence of Caligus mugilis Brian (Copepoda, Siphonostomatoida; Caligidae) with Morphological Characters in Turkish Marine Waters Ali Alaş 1 & Ahmet Öktener 2 Received: 13 January 2017 # Springer International Publishing AG 2017 Abstract The aim of this study is to determine Caligus mugilis including morphological characters on Mugil cephalus from Bandırma Bay in Turkey. The flathead grey mullet, Mugil cephalus were examined for the ectoparasites in 2016. Caligus mugilis Brian, 1935 (Copepoda, Siphonostomatoida, Caligidae) is confirmed for the first time in Turkish marine waters. Also, some morphological charac- ters of this parasitic copepod are described. All parasites were firmly attached to the gill filaments of the host. Parasite prev- alence, mean intensity and mean abundance were 9.3%, 1, 0.09, respectively. It should be noted that Caligus mugilis was reported by some researcher in 1989, however there was uncertainty about the occurrence of Caligus mugilis in Turkey. This controversial issue is cleared with this study. Keywords Caligus mugilis . Mugil cephalus . Sea of Marmara . Morphology . Turkey Introduction Flathead mullet, Mugil cephalus is a cosmopolitan fish spe- cies, widely distributed in coastal waters, lagoons, and estuar- ies between latitudes 42°N and 42°S (Thomson 1966). Flathead grey mullet has been farmed for centuries in exten- sive and semi-intensive ponds in many countries (FAO 2017). The wide-scale polyculture of mullet with carp and tilapia has been done in fresh water and brackish water ponds in Israel (Paperna and Overstreet 1981). Copepods of the family Caligidae (Siphonostomatoida) are commonly known as sea lice among the fish culturists. It is the largest family of marine copepods comprising over 450 spe- cies (Ho 2004). Atlantic salmon (Salmo salar) in the northern hemisphere are often infested with two species of sea lice: Lepeophtheirus salmonis and Caligus elongatus (Wootten et al. 1982; Pike 1989). Infestations cause erosion of skin, most often on or near the head. Heavily infected salmon die. Smolts newly introduced to sea water are the most susceptible (Wootten et al. 1982). In Israel, Pseudocaligus apodus has caused mortality in cultured mullet (Paperna and Lahav 1974). Wild fish are believed to be the primary reser- voirs of parasites infection for fish farmed in sea-cages, and can negatively impact upon the health of farmed fish (Antonelli and Marchand 2012). According to Bragoni et al. (1984,) Nerocila orbignyi infestations of the sea bass producing in the aquaculture conditions can be sourced by Mugil cephalus. Nine species of parasitic copepod ( Brachiella oblonga , Caligus pageti , Colobomatus mugilis , Ergasilus lizae , Lernaea * Ali Alaş alasali@hotmail.com 1 Department of Biology, A. K. Education Faculty, Necmettin Erbakan University, 42090 Meram, Konya, Turkey 2 Deparment of Fisheries, Sheep Research Institute, Çanakkele Street 7km., 10200 Bandırma, Balıkesir, Turkey Thalassas DOI 10.1007/s41208-017-0030-5