Seasonal dynamics and distribution of Philometroides fulvidraconi (Philometridae) in the bullhead catfish, Pseudobagrus fulvidraco (Richardson)

摘要

Philometroidesfalvidraconi Yu, Wu & Wang, 1993 was originally reported from three species of catfish, the bullhead catfish, Pseudobagrus falvidraco (Richardson), in Jiangkou Reservoir, Jiangxi Province and the middle reaches of the Yangtze River, the Chinese longsnout catfish, Leiocassis longirostris Giinther, and L. crassilabris Giinther, also in the middle reaches of the Yangtze. Adult females occur in the eyesocket and males and larvae on the surface of the internal organs and/or in the abdominal cavity of the fish (Yu, Wu & Wang 1993a). Its life cycle has been demonstrated experimentally, with the intermediate host a copepod, Thermocyclops taihokuensis, and catfish as the definitive hosts (Yu, Wang, Feng, Wu & Wang 1993b). Of the three species of catfish, the bullhead catfish is often very abundant in lakes, reservoirs and rivers, and despite its small size, is a commercially important species (Anonymous 1976; Cheng & Zheng 1987). Heavy infections of P. fulvidraconi were found only in the bullhead catfish in Jiangkou Reservoir where it was one of the most serious diseases (Pan 1988; Yu et al. 1993b). The major clinical signs of the disease include inflammation and engorgement around the