Chaetoceros muelleri is one of the most widely used microalgae species in aquaculture in northwestern Mexico as food for fish and crustaceans. Its importance is due to its fast growth, nutritional quality and lipid accumulation under nutrient-limiting conditions. However, the biochemical and molecular mechanisms of uptake of phosphorus (P) limiting conditions for this species is still unknown. This study aimed to analyze the growth and biochemical composition of C. muelleri in response to different phosphorus concentrations. Four treatments under different phosphorus conditions were used: control (72 μM P), excess (144 μM P) and two treatments with phosphorus limitation, limited A (18 μM P) and limited B (7 μM P). The highest cell concentration was observed in control and excess of P (>3.4×106 cells mL-1). The highest dry mass concentration and chlorophyll-a content were found in control medium (72 μM P) whereas the highest total lipid (4.42%) was found in the lowest P-concentration medium (7 μM P). No significant differences were found in the total protein content, but we did find differences between the treatments with phosphorus limitation (7 and 18 μM P).