Fish are prone to several parasitic diseases among which are the myxosporean infections. The goal of this study was to assess the prevalence and patterns of Myxobolus infection in O. niloticus in the Adamawa region of Cameroon. Specimens of Oreochromis niloticus were collected monthly in Mape dam from May 2016 to May 2017, and examined for Myxosporean infections. The overall prevalence was 45.43%. Myxobolus tilapiae significantly exhibited the highest prevalence (15.14%) followed by Myxobolus brachiosaurus (12.29%). Myxobolus pharyngeus (0.86%) was the less prevalent parasite. Out of 350 examined fish, 23.14% were poly infected. Five categories of polyinfections were observed i.e. bi (15.71%), tri (4.00%), tetra (2.29%), penta (1.14%) and hexa specific (0.57%) corresponding to two to six parasite species combinations respectively. Their prevalence dropped significantly with the number of coexisting species whatever the fish sex, class size, infection site and season. Kidneys harbored up to four categories of polyinfections, and Myxobolus tilapiae was the most associated contrary to Myxobolus agolus which appeared only in one combination of the tetra specific infection. Fish were significantly more poly infected during the dry season (28.76%) than the rainy season (18.78%). The polyinfection of O. niloticus with Myxobolus species is an alert calling for urgent control strategies.