Using copper sulfate to control egg fungus at Keo Fish Farm

Authors: Straus, David - Dave

Submitted to: Arkansas Aquafarming
Publication Type: Popular Publication
Publication Acceptance Date: 5/10/2016
Publication Date: 7/1/2016
Citation: Straus, D.L. 2016. Using copper sulfate to control egg fungus at Keo Fish Farm. Arkansas Aquafarming. 33(2):4.

Interpretive Summary:

Technical Abstract: Keo Fish Farm is the biggest producer of hybrid striped bass fry in the world. The hatchery manager asked about treatments to control fungus on eggs which occurred fairly often. Our lab has been working on gaining FDA-approval to use copper sulfate to control fungus on catfish eggs, so we were confident that we could help with their egg fungus problem. Copper sulfate is approved by the EPA for use in aquaculture as an algicide and molluscicide, but it is not approved by the FDA as a drug in aquaculture; however, regulatory action is deferred while we are working toward gaining approval of it to control Ich on channel catfish and saprolegniasis (fungus) on channel catfish eggs. Therefore, its use as a drug is currently acceptable. Hybrid striped bass hatch about 48 hours after spawning, so several quick treatments in a short time are necessary. The study used 3 concentrations (10, 20, and 40 ppm) based on what we found with catfish, and an untreated control. The treatments would begin the afternoon of spawning with a 10 min aerated, static bath and repeated the morning and afternoon of Day 2; eggs would not be treated after hatching began. This study confirmed that copper sulfate can be an economical and valuable resource in hatchery management for control of saprolegniasis in McDonald jars at a dose of 20 ppm. It is also currently being used for fungus control on mat-spawned largemouth bass eggs, and we have studies underway on rainbow trout eggs. This research has increased fry production at Keo by about 15 – 20%.