Pyrosomas are the large group of pelagic tunicates whose trophic role in pelagic communities has not yet been sufficiently studied. We ran across a local area of high concentration of the most widespread and commonest species of pyrosomas, Pyrosoma atlanticum, 450 miles off the Congo river mouth. The following was estimated: gut pigment content, defecation rate, organic carbon and pigment content of fecal pellets, and sinking rate. Based on these data and the measured number of pyrosomas colonies the grazing impact on phytoplankton and the fecal pellet flux were calculated. During the night swarms of 50–65 mm P.atlanticum removed 53% of phytoplankton standing stock in the 0–10 m layer; sparsely distributed pyrosomas consumed only 4%. The grazing impact in the 0–50 m layer was only 12.5 and <1% respectively. The fecal pellet flux resulting from nocturnal feeding of P.atlanticum while swarming made up 1.4–1.6 × 10⁶ pellets m⁻² 10 h⁻¹ or 305–1035 mg C m⁻² 10 h⁻¹ and 1.4 × 10⁵ pellets m⁻² 10 h⁻¹ or 87.4 mg C m⁻² 10 h⁻¹ while non-swarming. Incubation experiments showed the rapid degradation of fecal pellets at 23°C: the loss of pigment and carbon content was ˜60–70% after 45 h. We believe that given the sinking rate of 70 m day⁻¹ the main part of fecal material does not leave the upper water column and is retained in the trophic web of the epipelagic layer.