Studies in cage-cultured fish have reported spatial and temporal variations on parasite prevalence; however, most of these studies have been carried out in cold water and marine environments. Channel catfish, Ictalurus punctatus, is the main floating cages-raised species used in intensive fish culture in Tamaulipas. In Mexico, there are no seasonal reports on fish parasites in this type of cage system. The aim of the present study was to determine the prevalence and mean intensity of ectoparasites of cage-cultured channel catfish in a year. Fish were sampled bimonthly from six locations in Tamaulipas and measured and evaluated for ectoparasites. Results showed the presence of two gill-dwelling metazoans, Ligictaluridus floridanus and Ergasilus cerastes and one skin-dwelling protozoan, Trichodina sp.; a pattern characterized by peaks in prevalence in early autumn for L. floridanus and late autumn for E. cerastes was observed. In addition, geographic location had a significant effect on the prevalence of L. floridanus and E. cerastes. It was also observed that presence of these parasites was not associated with any fish mortality. To our knowledge, this is the first seasonal study on ectoparasite prevalence on channel catfish reared in cages in México.