FDA indexes antiparasitic drug for treatment of white spot disease in ornamental finfish

The US FDA has added Faunamor, an antiparasitic and antimicrobial product for ornamental finfish, to its Index of Legally Marketed Unapproved New Animal Drugs for Minor Species, making the drug legally available in the US for treatment of Ichthyophthirius multifiliis infections, commonly called “Ich” or white spot disease.¹

I multifiliis is a highly contagious protozoal parasite that commonly affects ornamental fish—including tropical fish, goldfish, and koi—kept in home aquariums and hobby ponds. The organism can be introduced into aquatic systems through infected fish or contaminated equipment and may spread rapidly throughout a tank or pond, potentially causing high mortality if left untreated. Clinical signs often include small white spots on the skin or gills, lethargy, and reduced appetite.¹

Faunamor contains 3 active ingredients—methylthionine chloride, malachite green oxalate, and acriflavine chloride—and is administered as an immersion treatment in aquarium water. The product combines antiparasitic and antimicrobial activity and is intended to treat both white spot disease and associated bacterial infections in ornamental finfish.¹ According to the FDA, Faunamor is currently the only drug legally marketed in the United States specifically for the treatment of Ich in ornamental finfish. Previously available products used for this purpose were unapproved and had not undergone FDA evaluation for safety and effectiveness.¹

The drug was added to the index through the FDA’s minor species indexing pathway, which allows certain animal drugs intended for non–food-producing minor species to be legally marketed without full approval. As part of this process, a qualified expert panel reviewed available data and determined that the benefits of using Faunamor outweigh the risks for the target species.²

Evidence reviewed by the panel included literature on the drug’s active ingredients, manufacturer studies evaluating efficacy and safety across multiple ornamental fish species, and expert experience with the product in the ornamental fish industry. In one study, Faunamor effectively eliminated or significantly reduced infestations of I multifiliis in 19 fish species with heavy parasite burdens.¹

Faunamor will be marketed over the counter in 20-mL and 100-mL bottles. The product is intended for use in aquariums, tanks, ponds, or other contained aquatic systems housing ornamental fish. It is not intended for use in food-producing animals.²

References

1. FDA announces new drug for treating common disease in ornamental pet fish. FDA. April 8, 2025. Accessed March 6, 2026. https://www.fda.gov/animal-veterinary/cvm-updates/fda-announces-new-drug-treating-common-disease-ornamental-pet-fish
2. Crossley KC. Drug for treating common disease in pet fish is now legally available. dvm360. April 8, 2025. Accessed March 6, 2026. https://www.dvm360.com/view/drug-for-treating-common-disease-in-pet-fish-is-now-legally-available