DAO 114:263-268 (2015)  -  DOI: https://doi.org/10.3354/dao02861

NOTE
Histological evaluation of sodium percarbonate exposure on the gills of rainbow trout

James M. Forwood1,*, James O. Harris1, Matt Landos2, Marty R. Deveney3,4

1School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
2Future Fisheries Veterinary Services Pty Ltd, East Ballina, NSW 2478, Australia
3South Australian Research and Development Institute (SARDI), and 4Marine Innovation South Australia (MISA), West Beach, SA 5024, Australia
*Corresponding author:

ABSTRACT: Ichthyophthirius multifiliis is a recurring problem in Australian rainbow trout Oncorhynchus mykiss farms and requires strategically timed, repeat treatments for effective management. Sodium percarbonate (SPC) is permitted for use in Australia, with host safety margins based on the toxicity of acute exposures to hydrogen peroxide (HP), the active product released when SPC is added to water. The effects of exposure to HP released by SPC, of repeated doses and of doses exceeding 100 mg l-1 on rainbow trout are unknown. We exposed juvenile rainbow trout (mean weight: 30.5 ± 9 g) to repeated doses of 50, 150 and 250 mg l-1 SPC for 1 h on Days 1, 2, 7 and 8 of a treatment regime. The effect of SPC was assessed by histological evaluation of structural changes in gill tissue. Survival was 100% in all groups, but some fish exposed to 250 mg l-1 SPC displayed impaired swimming performance, and on Day 9 after the final treatment, oedema was present in 9.8% of lamella, which was significantly higher than the mean occurrence of 1.7, 4.2 and 1.3% in fish treated with 0, 50 and 150 mg l-1 SPC, respectively. These changes resolved within 24 h of the cessation of treatment. We conclude that SPC is safe to use on rainbow trout in doses of ≤150 mg l-1 at 17°C, however caution is advised at doses approaching 250 mg l-1. Water temperature, fish age, fish size and maturity, intensity of parasite infection and stocking density could alter the sensitivity of rainbow trout to SPC treatments.


KEY WORDS: Oncorhynchus mykiss · Sodium percarbonate · Gills · Histology


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Cite this article as: Forwood JM, Harris JO, Landos M, Deveney MR (2015) Histological evaluation of sodium percarbonate exposure on the gills of rainbow trout. Dis Aquat Org 114:263-268. https://doi.org/10.3354/dao02861

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