Ключевые слова: chitose, chitose river, dace, during the breeding season, fish, flock, freshwater fish, hokkaido, japan, japanese dace, marriage color, martaugui, nuptial color, nuptial coloration, pacific redfin, redbelly dace, redfin dace, redside dace, river, stream, tribolodon brandtii maruta, tribolodon hakonensis, under water, underwater, underwater photography,