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Experimental infection of rainbow trout with Saprolegnia parasitica

Journal of Aquatic Animal Health

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Abstract

A method was developed to experimentally induce saprolegniasis in rainbow trout Oncorhynchus mykiss. The development of a reliable method to produce infected fish is essential to efforts to determine the efficacy of various antifungal treatments. Three methods for inducing saprolegniasis were evaluated in waters containing known concentrations of Saprolegnia parasitica zoospores. These methods included application of the following stressors to fish: (1) abrasion and dewatering, (2) water temperature increase, and (3) a combination Cif abrasion, dewatering, and temperature increase. Neither physical abrasion nor temperature increase stress alone was effective for inducing saprolegniasis. Only 25.9% of fish stressed by abrasion and dewatering alone became infected. Application of both abrasion and temperature stress, however, induced saprolegniasis in 77.8% of fish tested. Most of these fish became infected after 5 d of stress treatments. No fish became infected or died in the positive control group (not stressed but exposed to S, parasitica zoospores) or the negative control group (not stressed or challenged). This method should enable researchers to induce saprolegniasis in rainbow trout to study its pathogenesis or to test the efficacy of antifungal treatments. In conducting efficacy studies, it is important that therapeutic treatments begin promptly after the first signs of saprolegniasis are observed because the disease can progress very quickly and often results in mortality.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Experimental infection of rainbow trout with Saprolegnia parasitica
Series title:
Journal of Aquatic Animal Health
Volume
10
Issue:
4
Year Published:
1998
Language:
English
Contributing office(s):
Upper Midwest Environmental Sciences Center
Description:
pp. 397-404
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Aquatic Animal Health
First page:
397
Last page:
404
Number of Pages:
8