Location: Harry K. Dupree Stuttgart National Aquaculture Research CntrTitle: Control of Saprolegniasis on sunshine bass eggs with copper sulfate
|Straus, David - Dave|
|Ledbetter, Cynthia - Cindy|
|WILLIAMS, RICK - Keo Fish Farm|
|CLARK, MIKE - Central Arkansas Fisheries|
|FREEZE, MIKE - Keo Fish Farm|
Submitted to: International Conference on Diseases of Fish and Shellfish
Publication Type: Abstract Only
Publication Acceptance Date: 4/27/2015
Publication Date: 9/6/2015
Citation: Straus, D.L., Beck, B.H., Farmer, B.D., Ledbetter, C.K., Williams, R.S., Clark, M.L., Freeze, M.T. 2015. Control of Saprolegniasis on sunshine bass eggs with copper sulfate [abstract]. 17th EAFP International Conference on Diseases of Fish and Shellfish, September 7-11, 2015, Las Palmas. p. 190.
Technical Abstract: A major obstacle to successful hatchery production is water-mould (Saprolegniasis) growth on eggs. Copper sulfate (CuSO4) is commonly used to control Saprolegnia species in channel catfish hatcheries that use troughs, but the effectiveness of it on fish eggs hatched using different systems was not known. Therefore, the range-finding study consisted of three CuSO4 concentrations (10, 20, and 40 mg/L) and an untreated control (n=3). Female white bass Morone chrysops and male striped bass M. saxatilis were spawned, and eggs were transferred immediately to 6 L McDonald jars. After treatments to remove adhesiveness and to disinfect the eggs as in a typical hatchery, the 1 mm eggs were counted with an optoelectronic XperCount™ enumerator and transferred to each hatching chamber of our experimental system. Water flow maintained the rolling action of the eggs per industry standards. 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. The 3 – 4 mm fry were counted with the XperCount™ on Day 4. Water-mould samples from the controls were identified as Saprolegnia ferax. Saprolegniasis was severe in the untreated controls (28% survival). Very little water-mould 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 that confirmed maximum Saprolegniasis inhibition was achieved at 20 mg/L CuSO4.