Wild fish get a new FDA-approved sedation option for resource management

The FDA has approved eugenol immersion solution (AQUI-S E10%) for sedating freshwater finfish to a handleable condition, the agency announced August 25, 2026.¹ The approval covers field use only, meaning the product is meant for wild fish populations managed for resources, not for aquaculture or hatcheries.

Fisheries professionals routinely sedate fish to handle them for spawning, tagging, weighing, measuring, and collecting samples.² AQUI-S E10% is given as a static immersion bath. Fish are placed into a container of treated water individually or in small groups and removed once they're sedated enough to handle. Once they recover, they can be released directly back into the water.¹

Effectiveness across species

The US Fish and Wildlife Service tested the drug on a wide range of freshwater species, including rainbow trout, brown trout, cutthroat trout, lake trout, walleye, yellow perch, Nile tilapia, blue catfish, hybrid striped bass, channel catfish, common carp, and fathead minnows. Working with individual fish and small groups of 10 or 15, researchers recorded each fish's time to sedation, time to recovery, behavior during sedation and recovery, and fish length, then monitored the fish for survival over 24 hours.²

Salmonids treated at 25 mg eugenol/L sedated in 1.3 to 3.2 minutes on average and recovered in 3.6 to 10.8 minutes. Non-salmonids treated at 40 to 72 mg eugenol/L sedated in 0.9 to 3.1 minutes and recovered in 1.9 to 14.4 minutes.²

Transient behaviors including headshaking, coughing, and slight agitation were observed in some fish during initial exposure. These resolved within seconds, and the studies recorded no adverse reactions, with all fish surviving the 24-hour monitoring period, according to the FDA.²

Target animal safety

To establish safe exposure, the US Fish and Wildlife Service ran 3 margin-of-safety studies in fingerling rainbow trout, yellow perch, and channel catfish, dosing groups at the target sedation concentration, at a concentration 50% higher, and with no drug, across a range of exposure times. All 3 species showed an adequate margin of safety based on both concentration and duration of exposure. Researchers found no gross lesions in any fish, and histopathologic evaluation revealed no significant treatment-related changes. The only consistent behavioral finding was brief headshaking in the trout and perch during the first 15 to 30 seconds of exposure.²

Human food safety and user precautions

The FDA determined that when AQUI-S E10% is used according to the label, eugenol residues in the edible tissue of treated fish stay below the concentration considered safe for human consumers, so the drug does not pose a public health or food safety concern. The agency set the withdrawal period at 0 days for field use.¹ Because total residue concentrations fall substantially below the safe concentration for acute exposure to eugenol, the agency did not assign a tolerance.²

The label warns that AQUI-S E10% is harmful if swallowed and can cause an allergic skin reaction in some people. Anyone handling it should wear gloves, a lab coat, and eye protection, avoid skin and eye contact and ingestion, and wash their hands afterward.²

The FDA also updated its clove oil guidance to match the approval. Guidance for Industry #150, Concerns Related to the Use of Clove Oil as an Anesthetic for Fish, had warned that clove oil and its components, eugenol among them, weren't approved for fish. The agency revised it to list AQUI-S E10% as an approved sedative for freshwater finfish.

The FDA is allowing the product to be sold over the counter. AQUI-S E10% is sponsored by AQUI-S New Zealand Limited.

References

1. FDA approves eugenol sedative for field use in freshwater finfish. CVM Updates. US Food and Drug Administration. Published August 25, 2026. Accessed August 25, 2026. https://www.fda.gov/animal-veterinary/cvm-updates/fda-approves-eugenol-sedative-field-use-freshwater-finfish
2. Freedom of Information Summary. Original new animal drug application: NADA 141-630, AQUI-S E10% (eugenol immersion solution). US Food and Drug Administration; approved August 25, 2026. https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/18833