The only product in our lineup that is both an antibiotic and an antiparasitic — treats bacterial infections and internal parasites in one treatment.

Why Metronidazole is uniquely powerful: Metronidazole is the only product in our lineup that works as both an antibiotic and an antiparasitic. It belongs to the nitroimidazole class and is effective against anaerobic bacteria (bacteria that thrive without oxygen) as well as protozoan parasites — organisms responsible for conditions like hole-in-the-head disease, internal parasites, and certain freshwater ich-related complications. This makes it an essential tool when the cause of illness is uncertain or when a mixed bacterial-parasitic infection is suspected. Also commonly known as Flagyl.

About This Product

Metronidazole is a synthetic, broad-spectrum nitroimidazole-class antibiotic and antiparasitic. It works by entering microbial cells and disrupting DNA synthesis — killing both anaerobic bacteria and protozoan parasites from within. Because it specifically targets organisms that operate in low-oxygen environments, it is highly effective against infections that broad-spectrum antibiotics often miss.

Each tablet contains USP-grade Metronidazole — available in 250mg and 500mg strengths, both in 100-tablet counts. As the only dual-action antibiotic and antiparasitic in our collection, it is especially valuable when fish present with wasting, bloating, loss of appetite, or hole-in-the-head symptoms alongside bacterial signs — conditions that may involve both bacterial and parasitic causes simultaneously.

Also commonly searched as: fish metro, metronidazole for fish, fish zole equivalent, aqua zole equivalent, flagyl fish antibiotic, hole in the head fish treatment, fish internal parasite treatment, nitroimidazole fish antibiotic.

Commonly Treats

Bacterial Conditions: 

• Anaerobic bacterial infections
• Bacterial hemorrhagic septicemia
• Fin rot & tail rot\
• Dropsy (bacterial origin)
• Gill disease (anaerobic)

Parasitic Conditions:

• Hole-in-the-head disease (HITH)
• Internal protozoan parasites
• Hexamita & Spironucleus
• Bloat & wasting (parasitic)
• Loss of appetite (parasitic origin)

Directions for Use

1. Determine your dose: Use one 250mg tablet per 10 gallons of water, or one 500mg tablet per 20 gallons of water.
2. Dissolve the tablet in a small amount of aquarium water before adding to the tank. Stir until fully dissolved.
3. Add directly to your aquarium, pond, or hospital/quarantine tank.
4. Repeat every 24 hours for 5–10 days. Do not exceed 10 days of continuous treatment.
5. Perform a 25% water change each day before re-dosing to maintain water quality and reduce medication buildup.

Product Specifications

• For ornamental fish use only. Not intended for use in fish raised for human consumption.
• Not for human consumption. Do not ingest. This product is sold for aquarium fish treatment only.
• Keep out of reach of children. Store in a cool, dry place away from children and pets.
• Do not exceed 10 days of continuous treatment. Overuse may disrupt your tank's biological filter and contribute to resistance.
• Remove activated carbon from your filter before treatment — carbon will absorb the medication and render treatment ineffective.
• May affect biological filtration. Metronidazole can reduce beneficial bacteria populations in your aquarium. Monitor ammonia and nitrite levels during and after treatment and perform additional water changes if needed.

Label & Usage Disclaimer: Please read and follow all label directions before use. Product descriptions and usage instructions shown here are taken directly from the manufacturer’s product label and information provided by Montana Aquarium Supply. These statements do not represent the views or recommendations of Pittsboro Pet Supply or Pittsboro Feed. Made in the USA. Distributed by Montana Aquarium Supply – Billings, MT.