The article presents the original findings of Paracoenogonimus ovatus (Katsurada,1914) in fish in the Southern Bug and the Inhul rivers in Mykolaiv Region in 2012-2014. The roach (Rutilus rutilus), silver bream (Blicca bjoerkna), bream (Abramis brama), crucian (Carassius gibelio), rudd (Scardinius erythrophthalmus), pike (Esox lucius), pikeperch (Sander lucioperca) were found to be infected with metacercariae of P. ovatus. Metacercariae of P. ovatus are described based on the original material. The highest prevalence of infection was observed in the roach, 82.3 %, the pike was infected in the less degree, with prevalence of 15.3 %. The infection intensity was highest in the roach, up to 247 specimens; that of the pikeperch was the lowest - 17 specimens. The highest occurrence of P. ovatus was observed in the parts of the river Southern Bug in Zhovtnevy, Mykolaiv, Novoodesky Districts, whereas in Voznesenky, Pervomaysky Discticts and in the city of Mykolaiv the occurrence was the lowest. In the area of the river Inhul the parasite was observed mostly in the waters of Bashtansky District in Mykolaiv Region.
The article describes occurrence and distribution of Eustrongylides trematodes in fish in the waters of the Dnipro-Buh estuary and the delta of Dnipro River in Mykolaiv and Kherson Region. Study was conducted in 2015–2016. This parasite was found in natural water reservoirs in Mykolaiv and Kherson region in following fish species: Sander lucioperca (Linnaeus, 1758), Perca fluviatilis (Linnaeus, 1758) and Esox lucius (Linnaeus, 1758). Ichtyopathological investigation of 346 fishes was conducted. Parasites were observed in abdominal cavity, muscle tissue, wall of gastro-intestinal tract, gonads and hepatopancreas. P. fluviatilis was the most affected species, prevalence of infection was 85.1 %. Less infected were S. lucioperca and E. lucius, with the prevalence of infection 58.1 % and 58.9 % respectively. Mean prevalence of infection of predatory fish in studied reservoirs was 70.5 %. The intensity of infection was the highest in perch (1–14 nematodes per fish). The lowest intensity of infection was found in pike-perch (1–9 nematodes per fish).
The article describes occurrence and distribution of Cryptocotyle trematodes in fish in the waters of the Dnipro-Buh estuary and the Black Sea in Mykolaiv and Odesa Region. Study was conducted in 2015-2016. Two trematode species were found in natural waters of these regions: Cryptocotyle cancavum Crepli, 1825 and Cryptocotyle jejuna Nicoll, 1907. Th e latter species has not been previously registered in this region in southern Ukraine. Varying intensity of infection with Cryptocotyle metacercariae was observed in fish of Gobiidae family: Mesogobius batrachocephalus Pallas, 1814, Neogobius melanostomum Pallas, 1814, N. fluviatialis Pallas, 1814. Th e most affected species was N. melanostomum, with the prevalence of infection 59.2 %. Less infected were N. fluviatialis and M. batrachocephalus, with the prevalence of infection 30.4 % and 17 % respectively. The intensity of infection was the highest in N. melanostomum - 211 metacercariae per fish, followed by N. fluviatialis and M. batrachocephalu - 124 and 89 metacercariae respectively. Cryptocotyle was the most prevalent in the Dnipro-Buh estuary (cape Adzhigol, Mykolaiv Region) and much less prevalent in the waters of the Black Sea in Mykolaiv and Odesa Regions. Mean prevalence of infection was 31.4 %.