The feeding of spawning threespine stickleback Gasterosteus aculeatus L. during the entire spawning period (late May – early July) in 2016 has been studied in three locations of the Chupa Inlet mouth, Kandalaksha Bay, White Sea. The fish mostly feed on benthos: stickleback eggs (up to a half of stomach content), pupae and larvae of Chironomidae, Polychaeta and Amphipoda, and also on imago of ... [Show full abstract] Diptera. In good spawning grounds with high density of spawners, the proportion of stickleback eggs in feeding is higher. Effect of sex, spawning stage and location has been found. Females, in comparison with males, have a more diverse diet (20 food items versus 13) and show greater changes during the spawning season, in particularly, they consume more energetically-rich food items than males. This is likely because more territorial males, occupied with guarding the progeny, are more limited in changing their diet. Differences between the sexes are especially large by the end of spawning period. Females begin intensive post-spawning feeding before the males, which have to guard the nests. We also observed a decrease of condition factor during the spawning period, which is probably associated with high energetic cost of spawning.