This work characterizes the growth of mangrove oyster, Crassostrea gasar of two lagoons of Côte d’Ivoire: the Ebrié lagoon; on the level of Grand-Bassam and Azito and the Aby lagoon; on the level of Assinie. Thus, a monthly sampling of 30 oysters per site for 12 months (October 2015 at September 2016), during which the physico-chemical parameters of water were recorded. The results of the study show an almost similar evolution of the physico-chemical parameters of the three sites. However, the sites of Assinie and Azito recorded a salinity, although lower than 10‰, high compared to that of Grand-Bassam. The results of morphometric analyses plead in favour of a negative allometry for the two relations in particular, size-sizes relations and size-weight relations. However, the individuals of Assinie present the best values of growth coefficient (b). According to PCA, the individuals of Assinie are identifiable by a weight of flesh and a width of higher bodies. Those of Azito are characterized by a thickness of body, a weight of shell, and a body weight more marked. As for the individuals of Grand-Bassam, they don’t present any distinguishing mark making it possible to characterize them. This study shows, the necessity to install a durable strategy of management of oyster stocks of our lagoons. It would be interesting to envision the culture of the oyster which remains an important food product of socio-economic interest.