An experiment was carried out in rice field of Krishi Vigyan Kendra (KVK), Kumarakom during 2017 to 2018 to study the influence of rice-fish and rice-water fallow systems on carbon dynamics in Kari soil. The samples were analysed for bulk density, soil pH and soil C pools. Bulk density (BD) of the soil showed no significant difference between rice-fish and rice-water fallow systems. However significant difference was recorded between surface and sub surface soils with maximum in sub surface soils. Soil pH, soil organic C (SOC), Particulate organic C (POC) were found to be higher in rice-fish system compared to rice-water fallow system and surface soil contained higher pH, SOC, POC than sub surface soil. The treatments found to be non significant with respect to labile C (LC). The study revealed that the rice-fish system significantly increased the different C pools, soil pH compared to rice-water fallow system in Kari soils.