This study investigates the effect of social capital investment on poverty reduction among fish farming households of Oyo State, Nigeria. A multistage sampling technique was adopted in the selection of the respondents. Primary data were collected using a structured questionnaire from a representative sample size of 359 households in four local government areas representing the four agricultural zones, namely Ibadan-ibarapa, Oyo, Ogbomoso and Saki in Oyo State, Nigeria. The study used a multinomial logit regression model to examine the effect of social capital on household poverty. The estimates of the regression model indicated that, in addition to the socio-economic characteristics of some households, social capital endowments have significant effect on the probability of a household being poor. The study concluded that, among other factors, social capital is very important in reducing household’s poverty. It was therefore recommended that stakeholders should be encouraged to invest in households’ social capital to accelerate poverty reduction among the fish farmers in the study area.