Three-spined stickleback is one of the widespread fish species of East Murman. It is found in 13 catchment areas of the Barents Sea coast in the eastern part of the Murmansk region, including major rivers, shallow river basins and inter-basin spaces. Stickleback is found in such lakes as Enozero, Pervoe Titovskoe, Opasovskoe, Dolgoe, etc, and in the rivers Yokanga, Varzina, Kharlovka, Voronia, Teriberka, etc. There is no detailed biological description of stickleback in this area, and the information available only mentions its presence in water bodies and occurrence in the stomachs of predators. The present paper provides data on three-spined stickleback caught in the coastal region of the Barents Sea at a depth of 120–123 m. The marine form of stickleback spends entire life cycle in the sea. In the Barents Sea, stickleback has a pelagic way of life, going quite far from the shore. According to the published data, its habitat depth in the Barents Sea is 50–450 m, with an average of 270 m, where temperature varies from 0 to 4 °C, with salinity 33–35 ‰. It has been found out that stickleback is represented by two morphotypes – trachurus with a keel (98 %) and semiarmatus (2 %) with a keel. The study has revealed different number of lateral plates and the nature of their distribution on the body of stickleback. In the study area, individuals of different size groups could be found. On average their body length ranges from 51 to 60 mm with a maximum length of 81 mm; the weight changes from 0.79 to 1.39 g. The authors have observed positive allometry of the dependence of mass on body length. Proportion of empty stomachs is almost 100 % with the fat content 1–2 points. The gonads of males and females caught in August 2015 were in after spawning condition. Females comprise the majority of the population (65 %). Infestation of stickleback with helminths is insignificant. Larvae of Anisakis simplex nematode have been observed most frequently during the examination of internal organs and body cavity.