Polyguard Bacterial & Fungal Freshwater Fish Treatment

Grouped product items
2.2 lb Polyguard Bacterial & Fungal Fish Treatment

SKU: 213221

In stock


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As a blend of multiple antibiotics and anti-parasitic medications, Polyguard is one of Seachem’s strongest freshwater medications available. Polyguard is effective against common bacterial, fungal, and parasitic diseases that may affect freshwater tropical fish.


While we are often tempted to reach for the most powerful medication available, most often it is best for the fish if we attempt a proper diagnosis and treat with a gentler medication if possible, especially if the infection is not severe. As one of the strongest medications available, Polyguard is best reserved for times when diagnosis may be uncertain or when your fish may have multiple infections and a stronger treatment is necessary.


  • Broad spectrum medication blend
  • Treats bacterial, fungal and parasitic diseases
  • Good choice when unsure of the disease
  • Freshwater only


Disease treatment in a quarantine tank is always the preferred option. Since Polyguard contains multiple ingredients that are harmful to invertebrates such as snails and shrimp, this medication should not be used in their presence, or they should be removed prior to treatment. Always observe tank inhabitants carefully when treating, and be prepared to perform a water change and add fresh activated carbon if necessary. When the treatment period is over, Polyguard can easily be removed using activated filter carbon. It does not linger in the substrate or filter media of the tank.

Active Ingredients
Sulfathiazole (36%), malachite green (1.9%), nitrofurantoin (0.14%), nitrofural (0.14%), quinacrine dihydrochloride (0.27%). Inactive ingredients: excipients (61%)


Dosing Directions
• Remove all invertebrates - these are extremely sensitive to medication.
• Turn off UV filters, ozone filters, and remove chemical filtration media.
• Use 1 measure (included) per every 10 gallons (40 liters) of water.
• Repeat this dose every 72 hours for a maximum of 2 weeks.

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Product Questions

must I remove biological filter while using polyguard?
Question by: Ron on Nov 18, 2021, 8:43 PM
It is not necessary to remove biological filtration when using Polyguard. Polyguard my be harmful to some beneficial bacteria and we recommend using it in a hospital tank and not in an established system.
Answer by: William Glenn (BRS Staff) on Dec 13, 2021, 12:22 PM