Oreochromis mossambicus were sampled from a semi-intensively managed polyculture earthen pond in Bagauda, Nigeria for histopathological changes in the gills and liver as early warning signs of pond water pollution. Pond water was sourced from nearby Bagauda dam through a single 28 inches water pipe. The physicochemical parameters of the earthen pond water were within acceptable limits for the growth and survival of O. mossambicus. Although observed histopathological lesions were significantly (p<0.05) higher in the liver than in the gills of sampled fish, lesions were within the normal functioning of respective organs based on the degree of tissue change protocol. The observed lesions indicated low level pollution of the earthen pond water. The result of this preliminary work notwithstanding, there is a need for constant monitoring of the earthen pond water and its water source (Bagauda dam) for pollutants. This is to ensure the continuous well-being and increased productivity of stocked fish within the earthen pond because of the large catchment area being drained by the dam relative to increasing human anthropogenic activities within the area.