Inspired by the social behavior of cockroaches, the Roach Infestation Optimization (RIO) algorithm was developed. It employs three common behaviors of cockroaches: seeking the darkest location, socializing with nearby cockroaches, and accumulating hunger, which will cause them to abandon their comfort in darkness or socialization. Combined with evolutionary algorithms, more satisfactory results are achieved. Therefore, an adaptation of the Cmax parameter was proposed to balance exploration and exploitation, resulting in better algorithm convergence. As a result, the RIO algorithm with fuzzy adaptation produced better results than the original RIO when evaluated with various benchmark mathematical functions.