Distribution patterns of saprolegniosis cutaneous lesions in wild and farmed brown trout (Salmo trutta L.) obtained using a geographic information system (GIS)

A retrospective study was conducted using 250 clinical records of brown trout (Salmo trutta L.) with saprolegniosis by Saprolegnia parasitica, which had been collected from 8 rivers and 1 fish farm in the province of León (Spain). A geographic information system (GIS) was used to obtain skin lesion distribution patterns in males and females. Lesions in wild brown trout affected 15.31 ± 13.33% of the body surface, with a mean of 12.76 ± 6.56 lesions per fish. In addition, 51.23% of wild trout presented lesions with necrosis of the skin or fins. The pattern obtained when not distinguishing between sexes indicated that saprolegniosis lesions are mainly located above the lateral line and most frequently affect the dorsal cephalic region, the adipose fin, the peduncle and the caudal fin. However, differences were observed between males and females. Farmed trout presented a lower percentage of affected body surface (2.06 ± 4.36) and a lower number of lesions with and without necrosis because they received preventive treatment for saprolegniosis.     

霉病力克对鱼类真菌病的防治效果及电镜观察

用霉病力克水煮液对患有水霉病的加州鲈进行浸泡治疗,每天早晚各一次,浸泡一周。同时用间接免疫荧光法(IIF)观察霉菌孢子在鱼体上皮细胞(FEC)粘附情况,用电泳法分析霉菌孢子内的生化反应。结果显示,用霉病力克处理后,病鱼体表霉菌菌丝全部消失,霉菌孢子的粘附作用明显降低,孢子内的生化反应受阻。试验表明霉病力克具有抗水霉菌和抑制水霉菌孢子粘附的双重作用,值得进一步推广应用。     

The relationships between fish health, metabolic rate, swimming performance and recovery in return-run sockeye salmon, Oncorhynchus nerka (Walbaum)

The repeat swimming ability and oxygen uptake (Mo2) of adult sockeye salmon, Oncorhynchus nerka (Walbaum), were assessed at ambient water temperatures at three field locations along their migration route. Following these measurements, internal and external fish condition was evaluated according to United States Environmental Protection Agency guidelines. Here we report on the physiological characteristics of fish having either moderate or severe levels of disease and injury. Routine oxygen uptake (Mo2) did not differ between healthy fish and those with indices of ill health. In contrast, fish classified as sick, which included conditions of damaged internal organs, an Ichthyophonus spp. heart infection, a Saprolegnia spp. gill infection, and skin wounds, had a lower post-exercise Mo2 and were unable to repeat their critical swim speed (U(crit)) on the second swim test. Moderate levels of disease or injury did not significantly affect either U(crit) or post-exercise Mo2. We conclude that the ability of adult salmon to recover quickly from exercise may be a useful indicator of sublethal pathologies.     

Comparative efficacy of Pyceze® (bronopol) in controlling mortality of brown trout Salmo trutta eggs

The efficacy of Pyceze^® (Novartis Animal Vaccines) and Proxitane^® 0510 (Solvay Interox) in controlling the mortality of eggs was studied in brown trout Salmo trutta eggs under the usual incubation conditions in a hatchery affected by saprolegniosis. Eggs from eight spawnings and from two lines of brown trout were used. The cumulative mortality of eggs at the start of the eyed stage (M₁) and at hatching (M₂) was measured, as was the percentage of eggs with fungal infection at weekly intervals during the green stage. Mortality at M₂ with Pyceze^® ranged between 2.38% and 12.61% depending on the batch, with a mean of 6.10%. Mortality at M₂ with Proxitane^® varied between 5.83% and 43.86%, with a mean of 22.36%. Fungal colonization at the start of the eyed stage ranged between 0% and 0.15% when Pyceze^® was used and between 0.82% and 12.50% with Proxitane^®. Mortality rates were higher among those eggs left untreated. The results indicate that Pyceze^® (bronopol) is efficacious in controlling mortality caused by Saprolegnia spp. and other biological factors in fertilized brown trout eggs, as has been demonstrated previously in other salmonid species.     

溶壁酶体外抗同丝水霉活性研究

为探究溶壁酶对水产动物水霉病的预防和治疗效果,以同丝水霉(Saprolegnia monoica)为研究对象,溶壁酶设0、5、10、20、40、80 mg/m L共计6个浓度处理组,取浓度为103个/m L的水霉孢子菌悬液0.1 m L,涂布于不同溶壁酶浓度的马铃薯葡萄糖琼脂培养基(PDA)上,25℃培养5 d,以最低抑菌浓度为判定指标,研究溶壁酶溶解同丝水霉孢子的抑菌活性;在此基础上,以溶壁酶最低抑菌浓度30℃分别水浴2 h和4 h处理同丝水霉菌丝块,PDA培养基上25℃培养5 d,通过用体外抑菌试验、菌丝显微结构观察等方法,研究溶壁酶最低抑菌浓度对同丝水霉菌丝的抑菌活性,为进一步开发水产动物抗真菌(替代孔雀石绿)药物提供科学依据。结果显示,溶壁酶对同丝水霉孢子的最低抑菌浓度为20 mg/m L,通过间隔添加溶壁酶该浓度,72 h能够有效抑制同丝水霉菌丝的生长;溶壁酶30℃水浴处理同丝水霉菌丝块的时间(2 h和4 h)与溶壁酶溶解菌丝效果呈正相关。     

Dose-Confirmation of Copper Sulfate for Treating Fungus on Channel Catfish,Ictalurus punctatus,Eggs at a Commercial Hatchery

This study at a commercial hatchery was required by the U.S. Food and Drug Administration to provide independent substantiation of the results of previous laboratory dose-confirmation studies on the use of copper sulfate (CuSO₄) to control fungus (Saprolegnia spp.) on the eggs of channel catfish, Ictalurus punctatus. The study compared an untreated control group of eggs to eggs treated with 10 mg/L CuSO₄ in a flow-through system; mean water temperature was 23.5°C. Eggs were treated once daily until the embryos reached the eyed stage (5 treatments). Hatching was complete by day 11, and fry were counted to determine the percentage of survival in each treatment. Fungus was identified by polymerase chain reaction (PCR) as Saprolegnia spp. The mean survival in the control treatments was 4% and 40% in the CuSO₄ treatments; the latter survival was significantly higher, but still lower than normal. This study confirms that 10 mg/L CuSO₄ is an effective treatment to control fungus on catfish eggs when used daily until the eggs are eyed. However, continued treatment of eggs until hatching occurs may be warranted based on fungal growth rates observed after treatments were discontinued.