SUMMARY1 Naupliar and copepodid development times (DnandDc, respectively) of two African freshwater calanoids (Metadiaptomus meridianusandTropodiaptomus spectabilis) were measured on mono‐specific diets of comparably sizedChlamydomonas reinhardii, Scenedesmus acutus, Cryptomonassp.,Rhodomonas minuta, Cyclotella meneghiniana, andSelenastrum capricornutum, to test the nutritional adequacy of these algae. Comparisons were made at a standard temperature (17°C) and food supply level (1 mgCl−1).2 All diets other thanScenedesmusandSelenastrumsupported complete naupliar development at broadly comparable times within and between calanoids, apart from greatly protractedDnvalues forM. meridianusonCyclotella. Dcdurations were more variable between diet types, and bothChlamydomonasandCyclotellawere inferior or inadequate for copepodid development.3 Both naupliar and copepodid stages ingested radiolabelledScenedesmusandSelenastrumreadily. Comparative incorporation rate measures ofSelenastrumandCryptomonasrespectively exceeded estimated metabolic maintenance needs of stage 3/4 nauplii ofT. spectabilisby some 56% and 790%. Scope for growth (‘surplus’ energy) was accordingly fourteen‐fold greater onCryptomonasthan onSelenastrum /Scenedesmus. The dietary inadequacy of these two green algae is thus attributed largely to low digestibility, and perhaps some bioche