Table 1. Summary of non-native fish species occurrence found in each river (Pilica, Bzura and Skrwa Prawa).

Species	Common name	Pilica	Bzura	Skrwa Prawa
Babka gymotrachelus	racer goby	+	+	+
Neogobius fluviatilis	monkey goby	+	+	−
Proterorhinus semilunaris	western tubenose goby	+	+	+
Percottuss glenii	Chinese sleeper	+	+	+
Ameiurus nebulosus	brown bullhead	+	−	−
Carassius gibelio	gibel carp	+	+	+
Pseudorasbora parva	topmouth gudgeon	+	+	−
Cyprinus carpio	common carp	−	+	−