Аннотация:Chinese sleeper (Percottus glenii) is actively spreading across Europe. Several pathways for the invasions have been described over the network of freshwater bodies there. Moreover, enthusiasts of fishing often move them to every possible direction into new habitats for some reason. It was recently revealed that the Baltic Sea isalso a pathway for its spread. The source of the Chinese sleeper invasion in Europe was the eastern extreme of the Gulf of Finland of the Baltic Sea. The place of release (north of the Neva Bay) geographically belongs to the sea, but the water is practically fresh there due to the confluence of the full-flowing Neva River. Chinese sleepers have successfully settled in it, and fishermen still catch them there to release into new habitats. The active spread of Chinese sleepers through the Baltic Sea has not been reported so far. Salinity in the Baltic Sea is low, but it is still not a freshwater body. Only in the coastal zone the water is freshened being suitable for Chinese sleepers. These fishes gradually spread along the coasts in a western direction. In 2013, they were found in the canals of a nuclear power plant located on the southern coast of the Gulf of Finland at a distance of about 100 km from the place of release. Recently it turned out that they can also cover considerable distances in the open sea since they appeared near Gogland Island. The island is located in the center of the Gulf of Finland. The distance to the nearest point of the coast in the south is 55 km, in the north - 40 km. In 2017, a dead specimen was found on the shore of Gogland after a storm, and in 2021 live Chinese sleepers were observed at the coastline. One specimen was caught. The find was unexpected because Gogland Island seemed to be unsuitable for this species. Chinese sleepers in the Gulf of Finland were previously recorded only in highly freshened areas of shallow waters, where macrophytes are abundant. The waters around Gogland differ significantly from such habitat as the depth rapidly increases at the coastline there. The zone of shallow freshened waters at the coasts is extremely narrow, it is hardly more than a few meters or does not exist at all. Intentional release of Chinese sleeper by humans to the waters at the coasts of Gogland is unlikely. Fishing enthusiasts usually release these fishes into small lakes, where they like to sit with a fishing rod. The coasts of the Gogland Island of are of little use for this. Moreover, the human population is almost absent there. Most of the island is "abandoned". There are only small military posts, a weather station, and two lighthouses, where a small number of employees work. Probably, either adult Chinese sleepers or their juveniles got to the island due to storms and currents from the coastal zone of the Gulf of Finland. Further settlement by sea can be expected. South from the Gulf of Finland the Chinese sleepers already populated freshwater bodies, but they have not been reported from the northern mainland, i. e. territory of Finland. Most likely, they will settle there or have already settled. The finds near the Gogland Island once again showed that Chinese sleeper can be satisfied with an extremely small area, and therefore even small desalinated areas of the sea can serve as pathways for the invasions.