AbstractFeeding rates ofBrachionus plicatiliswere studied for two types of food — algaeMonochrysis lutheriand baker's yeastSaccharomyces cerevisae.The main regularities of changes in filtration rate and ration were studied in small culture volumes (1 ml) for adult amictic females depending on food concentration (1, 2, 4, 8 and 16 · 106cells · ml−1), ambient temperature (16 and 26 °C), and salinity (5, 10, 15, 20, 25 and 30 ppt).B. plicatilisration did not depend on the salinity, but was largely determined by temperature and food concentration. It was found that at 16 and 26 °C the dependence of the ingestion rate (ration) on food concentration differed greatly. A hypothesis was suggested to explain this phenomenon. A critical concentration of both types of food at which the increase in the rotifer ration ceased is 4 · 106cells · ml−1.This is the minimum “background” food concentration forB. plicatilismass cultivation.The average rations measured at the concentration ofM. lutheriandS. cerevisaeof 4 · 106cells · ml−1where 1.3 ± 0.1 and 4.8 ± 1.3 μg dry weight. · ind−1· day−1at 26 °C and 0.54 ± 0.1 and 1.9 μg d. w. · ind−1· day−1at 16 °C, respectively. The rations obtained in the laboratory were corrected for the conditions of rotifer commercial production in the open field in summer time. The correct values were 0.86 and 0.72 μg d. w. · ind