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ARS Home » Southeast Area » Stuttgart, Arkansas » Harry K. Dupree Stuttgart National Aquaculture Research Cntr » Research » Publications at this Location » Publication #339355

Research Project: The Role of Mucosal Surfaces and Microflora in Immunity and Disease Prevention

Location: Harry K. Dupree Stuttgart National Aquaculture Research Cntr

Title: Loss reduction in a rainbow trout recirculating aquaculture systems (RAS) by periodical disinfection with peracetic acid (PAA)

item MEINELT, THOMAS - Leibniz Institute Of Freshwater Ecology And Inland Fisheries
item PEDERSEN, LARS-FLEMMING - Technical University Of Denmark
item LIU, DIBO - Leibniz Institute Of Freshwater Ecology And Inland Fisheries
item Straus, David - Dave
item GOOD, CHRIS - Freshwater Institute

Submitted to: International Conference on Diseases of Fish and Shellfish
Publication Type: Abstract Only
Publication Acceptance Date: 5/10/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In a research rainbow trout (Oncorhynchus mykiss) RAS, two different sized raceways were operated with one common biofilter unit. The larger raceway was stocked with food fish, while the smaller raceway was stocked with juvenile trout. After removal of the food fish, juveniles were moved into free segments of the large raceway and the free segments of the small raceway were stocked with trout fingerlings. Due to disturbance of the system’s balance, there were considerable increases in losses, especially of juvenile fish. The juveniles showed symptoms of a bacterial gill disease (BGD) with dislodged operculi, swollen and anemic gills and lethargic behavior. The gills of the juvenile trout were characterized by hyperplastic gill infections of different severity, fusion of the gill lamellae and severe mucus secretion. A bacterial mixed flora with several potential fish pathogens (i.e., Pseudomonas fluorescence, Flavobacterium sp., Plesiomonas sp., Vibrio sp. Yersinia ruckeri and Aeromonas sp.) was detected. Studies of the adult rainbow trout yielded swollen, hyperplastic and, in some cases, thick mucous on gills, which were pale and anemic. Superficial erosions of skin, partial petechiae, ecchymosis and Saprolegnia were also detected. In trials (2014-2015), a strategy with the aim of reducing fish losses was developed. For this purpose, two PAA products were tested for their suitability as disinfectants in the RAS at different concentrations and application periods. The reduction of the microbial Colony Forming Units(CFUs), the fate of PAA and hydrogen peroxide, the change in fish health and the reduction of losses were recorded. The behavior of the fish and the degradation of PAA, as well as hydrogen peroxide, during the passage through the system were determined. Disinfection with 2 ppm PAA twice a week reduced the total microbial CFUs by approximately 97%. The clinical appearance of the trout improved with significant loss reduction in both, juvenile and adult rainbow trout.