Sand goby spot at the rear of the first dorsal fin, ringed with white. The fish has a slender body, and the head is about a quarter of the total length. The sand goby has two dorsal fins with a wider gap between them than the common goby ("Pomatoschistus microps"), the anterior one consisting of six soft spines and the posterior one eight to eleven soft rays. The pelvic fins are fused with the anal fins. There are 58 to 72 scales along the lateral line and these scales are rather smaller than those of the common goby. The caudal fin is
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