Investigation of the toxicological and histopathological effects of hydrogen peroxide bath treatments at different concentrations on Seriola species and the effectiveness of these treatments on Neobenedenia girellae (Monogenea) infestations

Autor: Hiroko Hagiwara, Noritaka Hirazawa, Ryoko Takano, Shiori Tsubone
Rok vydání: 2017
Předmět:
Zdroj: Aquaculture. 479:217-224
ISSN: 0044-8486
DOI: 10.1016/j.aquaculture.2017.05.019
Popis: Amberjack Seriola dumerili (Carangidae) and yellowtail S. quinqueradiata are important commercial fish species in Japan; however, they are susceptible to skin and gill monogeneans. Recently, a treatment of 75 ppm hydrogen peroxide (H2O2) for 30 min was found to effectively eliminate these monogeneans. However, histological analyses of the host fish subjected to treatments with lower H2O2 concentrations have not been performed to determine the influence of these treatments on fish. Therefore, we investigated the influence of a 100 ppm H2O2 treatment at 25 °C on the survival, swimming behavior, feeding behavior and the histopathology of S. dumerili and S. quinqueradiata compared with the 300 ppm treatment at 25 °C, which is the conventional concentration. We then evaluated the susceptibility of both species to infestations of the skin monogenean Neobenedenia girellae after the administration of a 75 ppm H2O2 bath treatment relative to the susceptibility after the administration of the conventional procedure (300 ppm for 3 or 4 min) at 25 °C. Both species suffered severe effects when exposed to 300 ppm H2O2; however, when exposed to 100 ppm H2O2 for 60 min, the survival, appetite, and swimming behavior were unaffected. Histopathological changes were not observed during the examination of the skin, gills, and internal organs of the fish in the control group and the group treated with 100 ppm H2O2 for 60 min, whereas histopathological changes were observed in the skin, gills and liver of the fish treated with 300 ppm H2O2 for 60 min, and the changes in S. dumerili became more pronounced with increasing exposure time. Furthermore, the fish treated with 75 ppm H2O2 baths for 30 or 40 min did not show increased N. girellae infestation levels relative to the untreated controls; however, the fish treated with the 300 ppm H2O2 baths for 4 min showed significantly increased N. girellae infestation levels relative to the untreated controls (P Statement of relevance To eliminate B. seriolae and N. girellae, Z. japonica, fish may be fed praziquantel-supplemented feed, submerged in a freshwater bath for 2- to 5- min, or placed in a hydrogen peroxide bath. However, none of these measures simultaneously dislodge B. seriolae, N. girellae, and Z. japonica. Orally administered praziquantel is ineffective against N. girellae infestations in Seriola species, and the freshwater treatment is not effective when the fish are infected with Z. japonica. Additionally, H2O2 treatment at a concentration of 300 ppm (conventional concentration in Japan) negatively affects fish health and viability, especially in the summer when water temperatures are higher and the parasite doubling and maturation rates are increase. Thus, any parasite control measure must be performed frequently during the summer. A bath treatment with 75 ppm H2O2 for 30 min effectively eliminates these parasites and the fish survival, appetite and swimming behavior were unaffected when exposed to 75 ppm H2O2 for 6 h at 25 °C. Therefore, treatment with 75 ppm H2O2 for 30 min is not expected to adversely affect S. dumerili. However, histological analyses of lower H2O2 concentrations have not been performed to determine the effects on the host fish, and experimental proof of the safety of different concentrations is important for the use of this treatment in aquaculture.
Databáze: OpenAIRE
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