Female adult specimens of the pennellid copepod Peniculus minuticaudae Shiino, 1956 were collected from the fins of two species of monacanthid fishes, threadsail filefish (Stephanolepis cirrhifer) and black scraper (Thamnaconus modestus), cultured in floating cages in Japan. These collections represent the first records of P. minuticaudae from farmed marine fishes as well as the first records of this copepod species from farmed S. cirrhifer and T. modestus. The finding of P. minuticaudae in this study is also the second record of pennellid copepods from maricultured fishes. Both the pectoral fins and the second dorsal fin were most heavily infected, followed by the caudal fin and the anal fin.