Background

Saprolegniasis often cause a significant economic losses to fish hatchery and intensive fish industry. The treatment of saprolegnoid diseases with malachite green seems to have harmful effect and is considered as a mutagenic and carcinogenic substance. The teratogenic and carcinogenic potential of malachite green increased the necessity to find an effective alternative treatment to control the disease.

Methods

In the present study, seven fungicides used in agriculture were investigated to control Saprolegnia parasitica and S. diclina in vitro. The antifungal activity of each fungicide was compared with that of malachite green as reference fungicide using food poisoning technique. Fish toxicity of the effective fungicides was performed to detect the most applicable fungicides in fish aquarium.

Results

Four of seven fungicides were found to be effective against the two saprolegnoid fungi. Azoxystrobin and metalaxyl were the most effective fungicides inhibited fungal growth of the two saprolegnoid fungi completely at concentration of 200 ppm and 250 ppm respectively while cyazofamid and etridiazole were moderately effective. Acute toxicity assay of the two effective fungicides showed metalaxyl was low toxic to fish with LC₅₀ of 360 ppm while azoxystrobin was 225 ppm. Hence, it was confirmed that 200 and 250 ppm of azoxystrobin and metalaxyl which completely inhibited mycelial growth of the saprolegniod fungi could be safely used for saprolegniasis control.

Conclusion

These fungicides which proved to be effective and fishery safer may be applicable as a aquatic fungicides avoiding teratogenic and carcinogenic risk of malachite green.

中文翻译：

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某些农业杀菌剂对两种腐生真菌感染养殖鱼类的抗真菌活性的体外评价

背景

腐烂病经常给鱼类孵化场和集约化鱼类产业造成重大经济损失。用孔雀石绿治疗腐烂性疾病似乎具有有害作用，被认为是诱变和致癌物质。孔雀石绿的致畸和致癌潜力增加了寻找控制该病的有效替代疗法的必要性。

方法

在本研究中，在农业中使用了七个杀真菌剂进行了研究，以控制水霉寄生和S.霉体外。使用食物中毒技术，将每种杀真菌剂的抗真菌活性与作为参考杀真菌剂的孔雀石绿的抗真菌活性进行了比较。进行了有效杀菌剂对鱼类的毒性检测，以检测鱼缸中最适用的杀菌剂。

结果

7种杀菌剂中有4种对两种腐生真菌有效。嘧菌酯和甲霜灵是最有效的杀菌剂，分别在200 ppm和250 ppm的浓度下完全抑制了两种腐生真菌的真菌生长，而cyazofamid和etridiazole的效果中等。两种有效杀真菌剂的急性毒性试验表明甲霜灵对鱼类的毒性低，LC ₅₀为360 ppm，而嘧菌酯为225 ppm。因此，证实了完全抑制腐生霉真菌的菌丝生长的200和250ppm的嘧菌酯和甲霜灵可以安全地用于腐生病防治。

结论

这些被证明是有效的和渔业安全的杀真菌剂可以用作水生杀真菌剂，避免孔雀石绿的致畸和致癌风险。