Nurullah2013-01-072013-01-072013-01-07sumarnihttp://repository.unri.ac.id:80/handle/123456789/1137Siak River is known as a river that has poor water quality in Riau due to pollutants. Water quality in the upstream, however is better than that in the downstream, as there is few pollutant agent enter the water body in that area. As water quality affect the growth of fish, fish that inhabit the upstream of the Siak River may grow up properly. Information on fish living in the upstream of the Siak River, however, is limited. Many studies focus more on the biology of fish living in the downstream of the Siak River. To understand the growth of fish from the upstream of the Siak River, this study was conducted. Fish growth was studied through investigating the growth ring pattern present in the otolith. The pattern was then compared with the otolith growth ring pattern of fish obtained from the Kampar River that has good water quality. In this study, Ompok hypophthalmus, captured from the Siak River (78 fish) and Kampar River (82 fish). The otolith (sagita) were removed and shaved using stone sharpener (following Windarti, 2007). Results shown that the otolith growth ring pattern of fish captured from both sampling areas was almost the same, they have 1-3 dark rings. The otolith weight of fish of the same size also not significantly different, the otolith of the Kampar’s fish is slightly heavier (3,2) than that of the Siak fish (5,9). This fact indicate that fish living in the upstream of the Siak River grow as well as fish living in the Kampar River and also indicates that the water in the upstream of the Siak River is suitable for supporting the life of fish living in that area.otherOtolithOmpok hypophthalmusUpstream Siak RiverGrowth ringArticle