DAO 146:9-21 (2021)  -  DOI: https://doi.org/10.3354/dao03617

ABSTRACT: Several biocides are widely used in rainbow trout aquaculture against various ectoparasites and ectobionts, but the inflammation induced in treated fish is less well described. Dose-response studies were conducted to elucidate the effects on rainbow trout (gills and fins) induced by a series of biocides including formalin, hydrogen peroxide (H₂O₂), peracetic acid (PAA) and the surfactant SPH6, which was isolated from the bacterium Pseudomonas H6. The compounds have documented antiparasitic effects, but the specific effects on fish needs further documentation. This study was performed over 24 h, and inflammatory reactions were evaluated in gills and fins. A dose-dependent effect was noted for expression of immune genes encoding for IL-1β, TNFα, IFNγ, IL-10, IL-8, lysozyme, serum amyloid A (SAA), hepcidin, precerebellin and complement factor C3. PAA induced the strongest upregulation of cytokine and acute phase reactant genes followed by H₂O₂ and formalin. SPH6 showed a lower effect, and in several cases the compound induced downregulation of several genes. Gills showed a stronger response compared to fins. The mucous cell density in fins showed a range of changes which varied by compound. PAA, and to a lesser degree H₂O₂ and formalin, initially induced mucous cell hyperplasia, whereas SPH6 immediately decreased the number of cells containing mucus.

KEY WORDS: Biocides · Inflammation · Cytokines · Gene expression

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Cite this article as: Mathiessen H, Marana MH, Korbut R, Wu B and others (2021) Inflammatory reactions in rainbow trout fins and gills exposed to biocides. Dis Aquat Org 146:9-21. https://doi.org/10.3354/dao03617 Export citation Share:    Facebook - - linkedIn