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US expands use of hydrogen peroxide in fish farming

Lahontan cutthroat trout diseases can be treated in the USA with 35% Perox-aid. Image: Fish and Aquatic Conservation/USA
Lahontan cutthroat trout diseases can be treated in the USA with 35% Perox-aid. Image: Fish and Aquatic Conservation/USA

The United States Food and Drug Administration’s Center for Veterinary Medicine has approved the use of 35% Perox-aid (hydrogen peroxide) for use in finfish environments.

“This approval will help provide a critical treatment for improving fish health. The agency also anticipates that resource management agencies will use this approved treatment for aiding in the restoration of certain freshwater fish populations,” said the FDA in a press release.

The usage approval of 35% Perox-aid will help control mortality rates among finfish, including “freshwater-reared cold water finfish, fingerling and adult freshwater-reared cool water finfish, and fingerling and adult freshwater-reared warm water finfish due to saprolegniasis”. Saprolegniasis is a disease affecting salmon eggs and juvenile fish in hatcheries and is caused by a pathogenic parasite. It causes lesions on the fish’s skin and in some cases it can cause respiratory distress and death.

Treatment and control

The approval allows treatment at different life stages other than just during the egg stage.

“The treatment and control of Gyrodactylus spp. in freshwater-reared salmonids is included. Gyrodactylus spp. are external parasites on the fish, making 35% Perox-aid a new option for treating parasites on fish; and the control of mortality due to external columnaris in all freshwater-reared warm water finfish.”

The US Fish and Wildlife Service, Association of Fish and Wildlife Agencies and the National Aquaculture Association conducted a survey in which saprolegniasis and Gyrodactylus spp. were among top concerns of finfish farmers.


“Studies showed that mortality associated with two different species of Saprolegnia was controlled in three different species of fish: rainbow trout, walleye, and channel catfish. Four field studies demonstrated the effectiveness of 35% Perox-aid for the treatment of Gyrodactylus spp. infestations in freshwater-reared salmonids, and two additional clinical field trials were conducted in largemouth bass and bluegill to extend the indication of control of mortality due to external columnaris disease to freshwater-reared warm water finfish,” said the release.

Previous use of hydrogen peroxide

Previously, hydrogen peroxide was approved in the US for a small number of fish-related issues, firstly to control mortality in freshwater-reared finfish eggs due to saprolegniasis.

It was then approved for freshwater-reared salmonids that had bacterial gill disease. It was also used for freshwater-reared cool water finfish with external columnaris disease. Columnaris, also known as cottonmouth, is common is the US and often fatal for fish that get the illness via the mouth and gills.