Large-scale lab culture of Ankistrodesmus gracilis and Diaphanososma birgei were evaluated by studying the biology and biochemical composition of the species and production costs. Ankistrodesmus gracilis presented exponential growth until the 6th day, with approximately 144 x 10(4) cells x mL(-1), followed by a sharp decrease to 90 x 10(4) cells x mL(-1) (8th day). Algae cells tended to increase again from the 11th day and reached a maximum of 135 x 10(4) cells x mL(-1) on the 17th day. D. birgei culture showed exponential growth until the 9th day with 140 x 10(2) individuals x L(-1), and increased again as from the 12th day. Algae A. gracilis and zooplankton D. birgei contain 47 to 70% dry weight protein and over 5% dry weight carbohydrates. The most expensive items in the context of variable costs were labor and electricity. Data suggested that temperature, nutrients, light availability and culture management were determining factors on productivity. Results indicate that NPK (20-5-20) may be used directly as a good alternative for mass cultivation when low costs are taken into account, promoting adequate growth and nutritional value for cultured A. gracilis and D. birgei.