Shredders are known to be the vital functional feeding group in the breakdown of the particulate organic matter in the river streams. Information on the functional feeding groups in the river streams is quite significant for understanding the breakdown of organic matter, energy flow along the river gradients, the trophic relationships and finally the management strategies to minimize activities that could lead to the impairment of the ecosystem functions. The role of shredders in the dynamics of both coarse particulate organic matter (CPOM) and fine particulate organic matter (FPOM) was investigated in Morogoro river found in Morogoro region. The samples of the shredders and the particulate organic matter were collected from the three zones of the Morogoro river. the upper, middle and lower zones. The results showed that the abundance and diversity of shredders (with the diversity index of 0.983) was significantly higher in upper zone of the river than in the middle and lower zones. This is supported by high leaf litter input in the upper reaches of the river. However, the quantities of CPOM showed no significant differences between the three zones of the river while the quantities of FPOM showed to be significantly higher in the lower reaches of the river than in the upper and middle reaches. These results indicates the high quantities of FPOM in the lower reaches of the river was strongly brought by the CPOM acted upon by the shredders in the upper reaches that are later washed to the downstream areas of the river. The highlights from this study is for further researches on the roles of shredders in aquatic trophic systems since they are still lacking especially in the tropical regions.