Blood fluke infection of cultured tiger puffer Takifugu rubripes imported from China to Japan

Abstract

Monthly samplings of tiger puffer Takifugu rubripes, which had been cultured in China and later introduced to a farm in Kagawa Prefecture, Japan, in May 2005, were conducted over a four-month period commencing in June 2005. Blood flukes were found in the visceral vascular system with the highest number being 162 worms/fish, and their eggs accumulated in the visceral organs. The parasite was classified within the genus Psettarium based on the unique male reproductive system, and tentatively designated as Psettarium sp. TPC (= tiger puffer from China). Molecular analyses, using the ITS2 rDNA gene indicated that the blood flukes of tiger puffer from two other sources (cultured in China and subsequently in the Kyushu area, and cultured in China only) were also Psettarium sp. TPC. This suggests that the infection cycle of Psettarium sp. TPC has been established in China. On the other hand, no evidence was found that its life cycle is complete in Japanese waters. Similar blood flukes were collected in 1993 from post-spawned tiger puffer caught in a set-net in Wakasa Bay, Fukui Prefecture and maintained there for several months. This parasite was differentiated from Psettarium sp. TPC by the presence of 5-6 rows of pre-oral spines and designated as Psettarium sp. TPJ (= tiger puffer from Japan). © 2007 The Japanese Society of Fish Pathology.