The argulid branchiuran, Argulus japonicus Thiele, 1900, is reported based on two males and a female from the body surface of a freshwater minnow, Opsariichthys platypus (Temminck and Schlegel, 1846) (Cypriniformes: Cyprinidae), held in a tank at the Banshō Sakana-no-yakata Aquarium, Saeki, Oita Prefecture, Kyushu, Japan. This is the first record of A. japonicus from the prefecture. The fishes held in the tank together with the infected freshwater minnow were cyprinids, which consisted of common carp Cyprinus carpio Linnaeus, 1758, ginbuna Carassius sp., gengorōbuna Carassius cuvieri Temminck and Schlegel, 1846, a species similar to ōkinbuna Cara-ssius buergeri buergeri Temminck and Schlegel, 1846, big-scaled redfin Tribolodon hakonensis (Günther, 1877), and kamatsuka Pseudogobio esocinus esocinus (Temminck and Schlegel, 1846), all of which had been collected from the Banshō River near the aquarium. It is thus likely that A. japonicus occurs in the river.

大分県で採集された淡水魚の外部寄生虫, チョウ Argulus japonicus(エラオ亜綱:チョウ科) (長澤和也・宮島尚貴)