Metronidazole Fish Antibiotics

Fish Zole is a broad spectrum metronidazole antibiotic that treats hole-in-the-head and angle problems in ornamental and aquarium fish. Fish Zole pet meds are effective against gram-positive and some gram-negative bacteria that cause a number of infections. The Forte version has twice the amount of Metronidazole as regular Fish Zole.

Fish Zole provides antibacterial, antiprotozoal, and antiparasitic benefits when used to treat aquarium fish. The medication is also effective against a range of infections in dogs and cats, including amoebiasis, trichomoniasis, giardiasis, and others.

Benefits of Fish Zole:

  • Well tolerated in fish and other animals
  • Protection against bacteria, parasites, and protozoa
  • May have immunostimulatory or immunosuppressive properties
  • Once-daily dosing for convenience
  • Treats entire tank of fish at one time
  • Improves health and activity level of aquarium fish

Use only as instructed. Read the product inserts and precautionary statements carefully before use.

Do not allow children to give or handle this medication. Not for use in humans.


  1. Add one 500 mg tablet or two 250 mg tablets into your aquarium for every 20 gallons of water.
  2. Perform a partial water change between 12 and 24 hours after administering the medication to the water.
  3. Repeat the dose 24 hours after the first dose was given.
  4. Repeat this schedule, including partial water changes, for between 5 and 10 days.
  5. Treat cats with 7.7 mg per pound of body weight every 24 hours, for 8 days.
  6. Treat dogs with 5.5 to 7 mg per pound of body weight every 12 hours for 8 days.

Frequency of Use:

Discontinue use of this medication if no improvement in your fish is noted after 5 days time. Continue treatment for a maximum of 10 days, or as instructed by your veterinarian.


Store Fish Zole in its original container, tightly sealed, and out of reach of children and pets.

It is a violation of Federal Law to use this product in a manner inconsistent with its labeling.

Fish Zole, and its active ingredient metronidazole, treat bacterial, parasitic, and protozoal infections in tank fish by disrupting the DNA of the infecting organism. Resistance is rare. Fish Zole is effective against Giardia.

Fish Zole is available over the counter.

Fish Zole (Metronidazole)

Active Ingredient: Metronidazole


Keep this product out of reach of children and animals. Do not use or store in or near open flame or heat.

Fish Zole is intended for use in aquarium fish. This medication may also be used in dogs and cats as prescribed by a veterinarian. Not for human use.

CAUTION: Do not give this medication to pregnant animals.

Overdose of this medication may cause lethargy, ataxia, vomiting, weakness, and CNS depression.

Consult your veterinarian if your pet experiences any side effects or adverse effects from use of this antibiotic.

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