Butterfly blenny Butterfly blenny The butterfly blenny ("Blennius ocellaris") is a small marine blenniid fish of Northern and Western Europe, as well as the Mediterranean and Black Seas and Morocco. It can grow as large as in length. It is usually found at a depth of down, especially in areas with a rocky floor. The butterfly blenny has 11–12 dorsal spines, 14–16 dorsal soft rays, 2 anal spines and 15–16 anal soft rays. It has tentacles on the nasal opening, above the eye and on the nape near the first dorsal fin ray. The lateral line is discontinuous. The forward part of
Round goby invasive nematode "Anguillicoloides crassus". In the Vistula Lagoon, the most abundant parasites of the round goby are nematodes "Hysterothylacium aduncum" and "Anguillicoloides crassus". 25 species of parasites are noted in the round goby in the Great Lakes. The trematode "D. spathaceum" is most abundant core species overall. Also the cestode "Proteocephalus" sp. and the trematode "Neochasmus umbellus" are rather abundant. The round goby may circumvent more of the metacercariae of "N. umbellus" from completing their life cycle. The parasite “load” on the invasive gobies in the Great Lakes appears relatively low in comparison with their native habitats, lending support to