|Straus, David - Dave|
|Ledbetter, Cynthia - Cindy|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/30/2013
Publication Date: 2/3/2014
Citation: Straus, D.L., Beck, B.H., Farmer, B.D., Ledbetter, C.K., Williams, R.S., Clark, M.L., Freeze, T.M. 2014. Copper sulfate controls fungus on sunshine bass eggs and increases survival [abstract]. Mid-Continent Warm Water Fish Culture Workshop 2014, February 3-5, 2014, Council Bluffs, Iowa. 2014:24. Interpretive Summary:
Technical Abstract: A major obstacle to sunshine bass production is fungal growth on eggs. Copper sulfate (CuSO4) is commonly used for fungus control in channel catfish hatcheries that use troughs, but the effectiveness of it on fish eggs hatched using different systems was not known. Female white bass Morone chrysops and male striped bass M. saxatilis were spawned, and approximately 120 ml of eggs were counted with an XperCountTM enumerator and transferred to each hatching chamber of our experimental system (below, left); water volume was 1.5 L. Water flow maintained the rolling action of the eggs per industry standards. The study consisted of three CuSO4 concentrations (10, 20, and 40 mg/L) and an untreated control (n=3). Because eggs start hatching after 2 d, treatment began immediately the afternoon of spawning with a 10 min aerated, static bath and was repeated morning and afternoon on Day 2. Eggs were not treated after hatching began. Fry were counted with the XperCountTM on Day 4. Water parameters were: pH 7.9, 216 mg/L alkalinity, and 266 mg/L hardness. Fungus samples from the control chambers were identified as Saprolegnia ferax. Fungus was severe in the untreated controls (28% survival). Very little fungus was present in treatments receiving 10 mg/L CuSO4 (32% survival) or higher. The best survival was at 40 mg/L CuSO4 (50% survival); however, the 20 mg/L CuSO4 treatment (46% survival) gave similar results and allows for a greater margin of safety. We developed an in vitro assay (below, right) that confirmed maximum fungal inhibition was achieved at 20 mg/L CuSO4.