Effects of Oxytetracycline Treatments on the Infection Potential of Scuticociliates in Cultured Olive Flounder, Paralichthys olivaceus

  • Kwon Se Ryun (Department of Aquatic Life Medicine, Pukyong National University) ;
  • Chung Joon Ki (Department of Aquatic Life Medicine, Pukyong National University) ;
  • Lee Hyung Ho (Faculty of Food Science and Biotechnology, Pukyong National University) ;
  • Kim Ki Hong (Department of Aquatic Life Medicine, Pukyong National University)
  • Published : 2002.03.01


The modulatory effects of oxytetracycline treatments at high concentrations on the infection potential of scuticociliates in cultured juvenile olive flounder (Paralichthys olivaceus) and density of the ciliates in culturing water were investigated. The groups bathed with 400 and 500 ppm of oxytetracycline showed significantly lower intensities of scuticociliates on the fish and considerably lower number of the ciliates in culturing water when compared with the control group. However, the intensity of scuticociliates on the fish in the group bathed with 300 ppm of oxytetracycline was not significantly different with that of the control group in spite of considerably lower number of scuticociliates in culturing water than in that of the control group. Although the intensities of scuticociliates on the fish intubated orally with 400 and 500 mg/kg of oxytetracycline were lower than that of the control group, there were no statistical significances. In contrast, the fish fed 300 mg/kg of oxytetracycline showed significantly lower intensity of scuticociliates when compared with other groups. The results of this study suggest that oxytetracycline treatments can modulate occurrence of scuticociliatosis in fish farms probably through change of bacterial density, damaging to scuticociliatosis and immuno-suppression of fish.


  1. Cheung, P.J., R.F. Nigrelli and G.D. Ruggien. 1980. Studies on the morphology of Uronema marinum Dujardin (Ciliatea: Uronematidae) with a description of the histo-patology of the infection in marine fishes. J. Fish Dis., 3: 295-303
  2. Cribb, A.E., B. Despres R.J. and Cawthorn. 1999. Tetrazolium -based cytotoxicityassay to determine anti-protozoal activity against the scuticociiate Anohryoides haemophila. Dis. Aquat. Org., 35: 213-219
  3. Crosbie, P.B.B. and B.L. Munday. 1999. Environmental factors and chemical agents affecting the growth of the pathogenic marine ciliate Uronema nigncans. Dis. Aquat Org., 36: 213-219
  4. Dragesco, A., J. Dragesco, F. Coste, C. Gasc, B. Romestand, J. Raymond and G. Bouix. 1995. Philastendes dicentrarchi, n. sp. (Ciliophora, Scuticociliatida), a histophagous opportunistic parasite of Dicentrachus labrax (Linnaeus, 1758), a reared marine fish. Eur. J. Protistol., 31: 327-340
  5. Dykov$\'{a}$, I. and A. Figueras. 1994. Histopathological changes in turbot Scophthalmus maximus due to a histophagous ciliate. Dis. Aquat. Org., 18: 5-9
  6. Fenchel, T. 1990. Adaptive significance of polymorphic life cycles in protozoa: responses to starvation and refeeding in two species of marine ciliates. J. Exp. Mar. Biol. Ecol., 136: 159-177
  7. Gill, P.A. and R.B. Calinan. 1997. Ulcerative dermatitis associated with Uronema sp. Infection of farmed sand Whit-ing Sillaeo ciliata. Aust. Vet. J., 75: 357
  8. Iglesias, R., A. Param$\'{a}$, M.F. Alvarez, J. Leiro, J. Fernandez, and M.L. Sanmartin. 2001. Philasterides dicentrarchi (Ciliophora, Scuticociliatida) as the causative agent of scuticociliatosis in farmed turbot Scophthalmus maximus in Galicia (NW Spain). Dis. Aquat. Org., 46: 47-55
  9. Lom, J. and I. Dykova. 1992. Development in aquaculture and fisheriesscience, Vol. 26. Protozoan parasites of flshes. Elsevier, Amsterdam, PP. 237-288
  10. Lunden, T., S. Miettinen, L.G. Lonnstrom, E.M. Lilius and G. Bylund. 1998. Influence of oxytetracycline and oxolinic acid on the immune response of rainbow trout (Oncorhyncbus mykiss). Fish Shellfish Immunol., 8: 217-230
  11. Munday, B.L., P.J. ODonoghue, M. Watts, K. Rough and T. Hawkesford. 1997. Fatal encephalitis due to the Scuticociliate Uronema niencaas in seacaged, southem bluefintuna Thuanus maccoyii. Dis. Aquat. Org., 30: 17-25
  12. Novotny, M.J., R.J. Cawthorn and B. Despres. 1996. In vitro effects of chemotherapeutants on the lobster parasite Anopbryoides haemophila. Dis. Aquat. Org., 24: 233-237
  13. Rijkers, G.T., A.G. Teunissen, R. Oosterom van and W.B. Muiswinkel van. 1980. The immune system of cyprinid fish. The immunosupprssive efct of the antibiotic Oxyte-tracycline in carp (Cypnnus carpio L.). Aquaculture, 19: 177-189
  14. Sterud, E., M.K. Hansen and T.A. Mo. 2000. Systemic infecion wjth Uronema-like ciliates in farmed turbot, Scophtalmus maximus (L.). J. Fish Dis., 23: 33-37
  15. Thompson, C.L. Jr. and L. Moewus. 1964. Miamiensis avidus n.g. n.s., a marine facultative parasite in the ciliate order Hymenostomatida. J. Protozool., 11: 378-381
  16. Yoshinaga, T. and J. Nakazoe. 1993. Isolation and in vitro cultivation of an unidentifled ciliate causing SCUtiCOCiha-tosis in Japanese flounder (Paralichthys olivaceus). Gyobyo Kenkyu, 28: 131-134