Summary1. The biovolume‐specific carbon content, relative egg volume (a measure of per‐offspring reproductive investment), growth and grazing rates, and the gross growth efficiency (GGE) of the rotiferCephalodella hoodi, isolated from an extremely acidic habitat (pH 2.65), were determined and compared with literature values for rotifers living in circum‐neutral habitats in order to reveal potential special features or adaptations related to the extreme habitat ofC. hoodi.2. Of the two dominant phytoflagellates (Ochromonassp. andChlamydomonas acidophila) that occur in the natural habitat ofC. hoodi, onlyC. acidophilapromoted positive growth and reproduction and, thus, the following results were obtained withC. acidophilaas a food alga.3. The body volume‐specific carbon content ofC. hoodiis in the range of that found in rotifers from circum‐neutral lakes, suggesting that no costly carbon investment, brought about by the thickening of the lorica, for example, was required to withstand low pH.4. The egg volume ofC. hoodiexhibited no phenotypic plasticity dependent on the food concentration and, thus,C. hoodiallocated a constant, absolute amount of energy to each individual offspring. No adaptation to low food densities was found.5. A dome‐shaped type II functional response curve was found to describe the ingestion ofChlamydomonasas a source of food.6. Compared with other rotifers,C. hoodihad a high threshold and half‐saturating food concentration (=low affinity) but also a high maximum growth rate and a relatively high GGE, suggesting no severe adverse effect of low pH.