ARS | Publication request: Using peracetic acid to control fungus on catfish eggs

Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: October 20, 2010
Publication Date: February 28, 2011
Citation: Straus, D.L., Mitchell, A.J., Meinelt, T. 2011. Using peracetic acid to control fungus on catfish eggs [abstract]. Book of Abstracts Aquaculture America. p.446.

Technical Abstract: A promising new treatment for parasites and egg fungi is peracetic acid (PAA; also called peroxyacetic acid). It is registered with the U.S. Environmental Protection Agency (EPA) as an oxidizing agent used as an antimicrobial compound approved for indoor use on hard, non-porous surfaces. This study looks at the use of PAA for fungus (Saprolegnia sp.) control in catfish hatcheries. A range-finding study was designed to determine the optimum concentration needed for fungus control on channel catfish eggs in 23.5°C well water. Channel catfish were spawned on-site and spawns were moved to the hatching lab within 24 hrs. Similar portions (~90 g) of a spawn were placed into mesh baskets of individual compartments of a custom hatching trough (n=4) and acclimated for 1 hr. Egg counts were also determined for each spawn to estimate number of eggs in each portion. The study consisted of 5 PAA concentrations (2.5, 5, 10, 15, and 20 mg/L) and an untreated control. Eggs were treated twice daily in a flow-through system until the hatching began. Water chemistry for the well water was pH 7.7, 243 mg/L total alkalinity, and 127 mg/L total hardness. When hatching was complete for all viable eggs, fry were siphoned into individual jars containing 70% ethanol and counted within a few days to determine the percent of fry that hatched in each treatment. Fungus was severe in the untreated controls (12% survival) and an optimum treatment of 2.5 mg/L PAA twice daily was sufficient to control fungus (60% survival). Very little fungus was present in treatments receiving 2.5 mg/L PAA or higher (Table 1), but at 15 ppm PAA and higher, toxicity to the eggs was observed and resulted in significantly lower hatch rates.