{"product_id":"kordon-methylene-blue-anti-fungal-treatment","title":"Kordon Methylene Blue | Anti-Fungal \u0026 Disease Prevention Treatment for Freshwater \u0026 Saltwater","description":"\u003cp\u003eKordon Methylene Blue is a trusted, broad-spectrum aquarium treatment that has been protecting fish from fungus, parasites, and respiratory distress for over 60 years. Available in a 4 fl oz (118 mL) hobbyist bottle or a 1 Gallon (3.8 L) shop-and-breeder size, it is safe for both \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/fresh-water\"\u003efreshwater\u003c\/a\u003e and \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/salt-water\"\u003esaltwater\u003c\/a\u003e aquariums and is a staple of any hobbyist's quarantine and disease-prevention kit.\u003c\/p\u003e\n\n\u003cp\u003eBrowse more in our \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/medication\"\u003emedication collection\u003c\/a\u003e or the broader \u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/maintenance-water-care\"\u003emaintenance \u0026amp; water care collection\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eWhy Hobbyists Trust Methylene Blue\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAnti-fungal \u0026amp; disease prevention\u003c\/strong\u003e — controls fungus on fish and prevents fungal growth on freshly-laid fish eggs.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTreats nitrite \u0026amp; cyanide poisoning\u003c\/strong\u003e — restores oxygen-carrying capacity of blood when fish suffer from \"brown blood\" disease.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMild parasite support\u003c\/strong\u003e — helps with external protozoan parasites including ich (white spot) and velvet when used as a dip or bath.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFreshwater \u0026amp; saltwater safe\u003c\/strong\u003e — formulated to work in both systems, ideal for quarantine tubs.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTwo sizes\u003c\/strong\u003e — 4 fl oz treats up to 360 gallons; the 1 Gallon size is sized for breeders, shops, and large quarantine systems.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eDosing \u0026amp; Usage\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eStandard tank dose:\u003c\/strong\u003e 1 teaspoon (5 mL) per 10 gallons of aquarium water. Repeat every 3 days with a partial water change in between if needed.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFish bath \/ dip:\u003c\/strong\u003e 1 teaspoon (5 mL) per 5 gallons in a separate container; bathe fish for up to 10 seconds to several minutes depending on tolerance.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eEgg fungus prevention:\u003c\/strong\u003e Add to a hatching tank at the standard dose to prevent fungus on developing eggs.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eImportant:\u003c\/strong\u003e Methylene Blue will stain silicone, decorations, and clothing blue. Use in a quarantine or hospital tank when possible. \u003cem\u003eDo not\u003c\/em\u003e use in a display tank with biological filtration — it can harm beneficial nitrifying bacteria. Not safe for live plants or invertebrates.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable style=\"border-collapse: collapse; width: 100%;\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eBrand\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003eKordon\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eProduct\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003eMethylene Blue — General Disease Prevention\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eSizes\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e4 fl oz (118 mL) and 1 Gallon (3.8 L)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eCoverage (4 oz)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003eTreats up to 360 gallons\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eActive Ingredient\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003eMethylene Blue (USP)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eWater Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003eFreshwater \u0026amp; Saltwater\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eUse For\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003eFungus, ich, velvet, nitrite poisoning, egg protection\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003e\u003cstrong\u003eReef \/ Plant Safe\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ddd; padding: 8px;\"\u003eNo — quarantine tank only\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eRecommended Pairings\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003ca href=\"https:\/\/squeakysaquatics.com\/products\/safety-stop-rapid-fish-quarantine-bath\"\u003eSafety Stop Rapid Fish Quarantine Bath\u003c\/a\u003e — pair with Methylene Blue for thorough new-fish quarantine.\u003c\/li\u003e\n  \u003cli\u003e\n\u003ca href=\"https:\/\/squeakysaquatics.com\/products\/polyp-lab-medic\"\u003ePolyp Lab Medic\u003c\/a\u003e — reef-safe ich \u0026amp; velvet treatment for display saltwater tanks.\u003c\/li\u003e\n  \u003cli\u003e\n\u003ca href=\"https:\/\/squeakysaquatics.com\/products\/hikari-prazipro-praziquantel-parasite-treatment\"\u003eHikari PraziPro\u003c\/a\u003e — pairs well for flukes and internal parasites in quarantine.\u003c\/li\u003e\n  \u003cli\u003e\n\u003ca href=\"https:\/\/squeakysaquatics.com\/products\/seachem-prime-water-conditioner-250ml\"\u003eSeachem Prime 250 mL\u003c\/a\u003e — water conditioner for setting up your QT system.\u003c\/li\u003e\n  \u003cli\u003e\n\u003ca href=\"https:\/\/squeakysaquatics.com\/collections\/water-testing\"\u003eWater testing kits\u003c\/a\u003e — monitor your QT parameters during treatment.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs methylene blue safe for plants and invertebrates?\u003c\/strong\u003e\u003cbr\u003eNo. Methylene Blue can damage live plants, snails, shrimp, and other invertebrates. It will also disrupt biological filtration. Always dose in a separate quarantine or hospital tank.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill it stain my silicone or decorations?\u003c\/strong\u003e\u003cbr\u003eYes — methylene blue is a strong dye and can permanently tint silicone seals, plastics, and porous decor. Use a dedicated QT setup with bare-bottom or expendable hardware whenever possible.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eHow often can I redose?\u003c\/strong\u003e\u003cbr\u003eStandard practice is to redose every 3 days alongside a 25% water change. Continue treatment for 5–7 days or until symptoms resolve.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCan I use it in a saltwater reef display?\u003c\/strong\u003e\u003cbr\u003eNo. Methylene Blue is not reef-safe. For display reefs, use a reef-safe option like \u003ca href=\"https:\/\/squeakysaquatics.com\/products\/polyp-lab-medic\"\u003ePolyp Lab Medic\u003c\/a\u003e instead.\u003c\/p\u003e","brand":"Kordon","offers":[{"title":"4 oz","offer_id":48600848367835,"sku":"37344","price":7.99,"currency_code":"USD","in_stock":true},{"title":"1 Gallon","offer_id":48600848400603,"sku":"37361","price":89.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0767\/5209\/3403\/files\/image_b95f49bd-9293-4f22-b93b-0a85893c5fdc.png?v=1776340325","url":"https:\/\/squeakysaquatics.com\/products\/kordon-methylene-blue-anti-fungal-treatment","provider":"Squeaky's Aquatics","version":"1.0","type":"link"}