The needs induced by the galloping demography and urbanization in the north-central part of Côte d'Ivoire have provoked strong anthropic pressures on the Bandama River, particularly its section located in the Haut-Bandama Wildlife reserve. This is reflected in the increased invasion of this watercourse by aquatic plants and algae, its enrichment in suspended matter and chemicals of all kinds. This state of the river could have repercussions on the development of biological organisms such as fish. Thus, the study aimed to determine the size structures and length-weight relationships of Brycinus imberi, Labeo coubie and Oreochromis niloticus from the Bandama River located in the Haut-Bandama wildlife Reserve. It was carried out along the longitudinal gradient (upstream-downstream) of the Bandama River, on 06 stations and during 08 sampling campaigns between January 2018 and February 2019. Fish specimens’ lengths measurements were made with an ichthyometer, and with an electronic scale, for the weights. The analysis focused on the size structure and length-weight relationships. Length-weight Relationship (LWR) was described by the equation: W = aLb. Brycinus imberi specimens’ sizes varied from 5.3 to 13.5 cm SL. At Labeo coubie, the specimens have sizes that oscillate between 7.6 and 51.2 cm SL. As for Oreochromis niloticus, the sizes were between 8.7 and 17 cm SL. Growth appeared allometric negative with b values of 2.70 for Brycinus imberi, 1.08 for Labeo coubie, and 2.51 for Oreochromis niloticus.