Ceratothoa oestroides

Ceratothoa oestroides is a parasitic isopod of the family Cymothoidae, being one of the "tongue biters" which are obligate ectoparasite of marine fish that dwells in the buccal cavity. It causes various pathologies in fish including tissue damage at the parasitisation site (tongue), growth defects, decrease in mean host weight and size, and increases mortalities in farmed and wild fish populations; fish from five different families are confirmed to host this species: Sparidae (Boops boops, Diplodus annularis, Pagelus erythrinus, Spicara smaris, Sparus aurata), Carangidae (Trachurus mediterraneus), Clupeidae (Sardina pilchardus), Scorpaenidae (Scorpaena notata, Scorpaena porcus), and Mugilidae (Liza aurata).

Mature individuals mate in the host's buccal cavity, and the resultant embryos develop in the female's marsupium, where offspring pass through different pullus stages until they are released from the marsupium as free swimming manca, ready to infest fish hosts. C. oestroides is one of the most devastating ectoparasites in Mediterranean aquaculture, with an unequal distribution along different geographical areas