Fish Pathology
Online ISSN : 1881-7335
Print ISSN : 0388-788X
ISSN-L : 0388-788X
Research Articles
Ceratothoa verrucosa (Isopoda: Cymothoidae) Infection in the Buccal Cavity of Red Seabream Caught in Iyo-Nada, Western Japan, with Some Notes on Its Co-infection with Choricotyle elongata (Monogenea: Diclidophoridae)
Tomomichi OhtaniIzumi KawamotoMasamitsu ChibaNoriyuki KuronoSatoru MatsuokaKazuo Ogawa
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2021 Volume 56 Issue 2 Pages 43-52


Long-term parasitological surveys were conducted on the isopod Ceratothoa verrucosa infecting red seabream Pagrus major caught in Iyo-Nada, Ehime Prefecture during the period of 2003–2007. ​The isopods were almost always in a pair of a male and a female, attached to the buccal cavity wall. ​The earliest infection occurred when seabream was 0+ year-old and the isopods grew as host fish grew. ​Prevalence of infection ranged from 12.2% to 21.2% when the host was 0+ to 5-year-old and decreased to 3.4% at 6-year-old and no infection among 7-year-old and older fish. ​These results suggest that infection was established when the host was 0+ year-old, and their life span of C. verrucose was estimated to be up to 6 years. ​Infected fish sometimes showed deformation in the upper jaw and growth retardation, but there was no evidence of infection-related mortality. ​The main reproduction season of the isopod was in summer, estimated by the presence of manca larvae in the marsupium of the female. ​Sometimes the monogenean Choricotyle elongata attached to the pleotelson of C. verrucosa. ​Prevalence and abundance of the monogenean were higher in the hyperparasitized seabream than in the fish without isopod infection, suggesting that the isopod favored the monogenean infection.

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© 2021 The Japanese Society of Fish Pathology
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