New data on the helminth fauna of Carassius gibelio (Bloch, 1782) from the Maritsa River, Bulgaria

This study aims to reveal the helminth diversity and infection parameters of the Prussian carp (Carassius gibelio) from the Maritsa River, Bulgaria. In 2024, fifteen specimens of Carassius gibelio were collected from the Maritsa River and examined for parasites. Sixty percent of the studied hosts harboured parasites. Two species of helminths were identified: one from the class Trematoda (Nicolla skrjabini) and one from the class Nematoda (Raphidascaris acus larvae). Raphidascaris acus larvae were distinguished by their high prevalence and are considered a core parasite species in the helminth communities of Prussian carp. Nicolla skrjabini is a component parasite species in the helminth communities of C. gibelio. Prussian carp is reported for the first time as a host for Raphidascaris acus larvae in the Maritsa River. The freshwater ecosystem of the Maritsa River is also a new locality record for Nicolla skrjabini in Bulgaria. Keywords: Carassius gibelio, Nicolla skrjabini, Raphidascaris acus, Maritsa River