Fix Zole (Fish Zole) Metronidazole Tablets - Fish & Bird Antibiotic 250 mg / 500 mg
Fix Zole (Metronidazole) 250 mg and 500 mg (previously known in the hobby as Fish Zole, Fish Zole Forte, or Aqua Zole) is a trusted fish and bird medication used by hobbyists to help manage protozoan flagellates such as Hexamita and Spironucleus, which are commonly associated with appetite loss, weight loss, and “hole-in-the-head” type symptoms in susceptible freshwater fish. Many keepers prefer treating in a hospital tank or quarantine setup for easier observation and control.
Metronidazole is a nitroimidazole medication with activity against certain protozoa and anaerobic organisms by disrupting DNA processes in susceptible targets. When used as directed, it can be part of a broader care plan that also includes stable water quality, reduced stress, and good nutrition. It is not intended for ich or flukes, and it is not a first choice for typical fin rot unless a professional has confirmed the cause.
Fix Zole from Aqua Soma Labs delivers 250 mg or 500 mg metronidazole per tablet and is available in 60-count bottles, making it easier to choose a strength that fits your tank size and treatment plan without complicated splitting or measuring. Tablets can be pre-dissolved in a small cup of aquarium water for more even distribution in a treatment tank.
Important Notice: This product is intended for aquarium and ornamental fish and pet birds only. It is not for human consumption or for animals used for food. We do not sell or recommend this product for human use.
Use Fix Zole when fish show persistent appetite changes, weight loss, or other signs consistent with protozoan flagellate issues, or when an avian veterinarian has recommended metronidazole for a confirmed protozoal concern in a non-food pet bird. Supporting treatment with clean water, stable temperature, and appropriate husbandry helps reduce setbacks and improve outcomes.
What Are the Benefits of Fix Zole (Fish Zole) Metronidazole 250 mg / 500 mg for Fish & Birds?
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Targeted Protozoan Support
Commonly used to help manage protozoan flagellates such as Hexamita and Spironucleus, which are often associated with appetite loss, weight loss, and "hole-in-the-head" type signs in susceptible freshwater fish.
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Avian Vet-Guided Option
In non-food pet birds, metronidazole may be used under avian veterinary guidance for certain protozoal concerns such as trichomonosis (canker), especially in pigeons and related species.
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Flexible 250 mg or 500 mg per Tablet
Choose the strength that fits your setup and plan. Consistent mg per tablet (in 60-count bottles) makes it easier to scale a treatment approach across different tank sizes or care routines.
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Ideal for Hospital Tanks and Quarantine
Many hobbyists treat in a separate hospital tank for better observation and to help protect the display tank's biofilter and sensitive tank mates. Tablets can be pre-dissolved in a small cup of aquarium water for more even distribution.
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Fits a Complete Care Plan
Best results come from combining treatment with stable temperature, clean water, reduced stress, and appropriate nutrition, rather than relying on medication alone.
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Targeted, Not a One-Size-Fits-All Remedy
Fix Zole is not typically used for ich (white spot), gill flukes, or Costia, and it is not a first choice for typical fin rot unless the cause has been confirmed. If symptoms persist, confirm the diagnosis or consult an aquatic or avian professional.
How to Dose & Use Fix Zole (Fish Zole) Metronidazole 250 mg / 500 mg for Fish & Birds
Directions for Use:
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Set Up a Separate Treatment Area
Move affected fish to a dedicated hospital tank when possible. This helps you monitor behavior, control dosing more precisely, and reduce unnecessary exposure in the display aquarium.
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Dose for Fish Aquariums (Label-Style Directions)
You may pre-dissolve the tablet in a small cup of aquarium water, then distribute evenly in the treatment tank:
Repeat the dose every 24 hours, performing a partial water change between treatments.
Tip: Remove activated carbon or other chemical filtration media during treatment and keep good aeration running, since carbon can reduce medication availability in the water.
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Continue the Course and Monitor Results
Continue daily treatment for 5 to 10 days (do not exceed 10 days). If there is no improvement within 5 days, discontinue treatment and consult an aquatic professional.
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Use in Pet Birds (Under Veterinary Guidance)
Only administer metronidazole to non-food pet birds under the direction of an avian veterinarian. Your vet should confirm the diagnosis and advise the correct mg-per-kg dose, frequency, and duration. Tablets may be given whole, split, or crushed and mixed into soft food exactly as instructed.
Pro Tip: After treatment, perform a partial water change and reintroduce activated carbon (if you normally use it) to help remove residual medication from the water.
What Makes Fix Zole (Fish Zole) Metronidazole 250 mg / 500 mg Effective?
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Active ingredient: Metronidazole (250 mg or 500 mg per tablet)
Metronidazole is a 5-nitroimidazole medication that is activated in susceptible anaerobic organisms and certain protozoa. During activation, short-lived reactive intermediates can damage DNA and disrupt cellular function in these targets. Hobbyists may also recognize metronidazole tablets under earlier names such as Fish Zole, Fish Zole Forte, and Aqua Zole.
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Inactive ingredients:
Like most tablets, Fix Zole includes inert excipients (such as binders and stabilizers) that help the tablet hold its shape, store well, and dissolve/disperse when mixed with water. The exact excipient list is not always published and may vary by batch.
Side Effects & Safety Tips for Fix Zole (Fish Zole) Metronidazole 250 mg / 500 mg
When used as directed, Fix Zole (metronidazole) is generally well tolerated in ornamental aquarium fish and non-food pet birds. Incorrect dosing, prolonged use, unnecessary repeat courses, or combining treatments can increase the risk of stress and side effects.
Quick safety checklist:
Treat in a hospital or quarantine tank when possible.
Remove activated carbon and other chemical filtration media and turn off UV sterilizers during treatment.
Maintain strong aeration and monitor ammonia and nitrite closely.
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Fish: Possible reactions include temporary reduced appetite, mild lethargy, or hiding behavior. If you see severe distress (rapid gill movement, loss of balance, gasping at the surface, or lying on the bottom), stop treatment, increase aeration, perform a partial water change, and seek aquatic veterinary advice.
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Birds: Use metronidazole only under avian veterinary guidance. Possible reactions may include decreased appetite, loose or changed droppings, and lethargy, especially if the bird is sensitive or the dose is not correct. If your bird appears fluffed up, inactive, or stops eating, discontinue use and contact an avian veterinarian.
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Invertebrates: Sensitivity can vary by species. Whenever possible, treat fish in a separate hospital tank instead of dosing a display aquarium that contains shrimp, snails, corals, or other invertebrates. If needed, relocate sensitive invertebrates before treatment.
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Safe use in your system: Do not mix Fix Zole with other antibiotics or medications unless advised by a professional. Avoid routine “preventative” dosing. If symptoms persist or return, confirm the diagnosis before repeating a course.
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Storage & handling: Store at controlled room temperature of 59 to 86 F (15 to 30 C) in a cool, dry place. Keep the container tightly closed to protect tablets from moisture and light. Keep out of reach of children and pets.
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Important safety warning: Fix Zole is intended for ornamental aquarium fish and non-food pet birds only. It is not for human use and not for animals raised for food. Always follow label directions.
Shipping & Returns
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FAQs About Fix Zole (Fish Zole) Metronidazole 250 mg / 500 mg for Fish & Birds
What is Fix Zole used for in aquarium fish and pet birds?
Fix Zole (metronidazole) is commonly used by hobbyists to help manage certain protozoan concerns in ornamental aquarium fish, including issues often associated with Hexamita or Spironucleus. In non-food pet birds, metronidazole may be used only under avian veterinary guidance for confirmed protozoal concerns such as canker (trichomonosis).
Is Fix Zole the same as Fish Zole or Fish Zole Forte?
Fix Zole contains the same active ingredient hobbyists have historically searched for as Fish Zole, Fish Zole Forte, or Aqua Zole (metronidazole). Product names, strengths, and directions can vary, so always follow the instructions for the specific product you have.
How do I choose 250 mg vs 500 mg tablets?
For aquarium dosing by water volume, choose the strength that matches your tank size and makes measuring easier. A common label-style approach is one 250 mg tablet per 10 gallons (38 L) or one 500 mg tablet per 20 gallons (76 L). Do not select strength based on "mild vs severe" without professional guidance.
Does metronidazole help with "hole-in-the-head" symptoms?
Metronidazole is commonly used when "hole-in-the-head" type signs are suspected to be linked to protozoan flagellates (such as Hexamita or Spironucleus). Not all cases have the same cause, so stable water quality, nutrition, and diagnosis matter just as much as medication.
Will Fix Zole treat ich (white spot) or gill flukes?
No. Metronidazole is not typically used for ich (white spot) or gill flukes. If symptoms suggest ich or flukes, choose a treatment that targets those parasites instead of using an antibiotic.
Can Fix Zole treat fin rot or other bacterial infections?
Metronidazole is mainly chosen for certain protozoan concerns and anaerobic-sensitive issues. It is not a first choice for typical fin rot unless a professional has confirmed the suspected cause and recommended metronidazole as part of a plan.
Can I use Fix Zole to prevent infections or as routine "preventative" dosing?
No. Fix Zole is intended for active, suspected, or confirmed issues, not routine prevention. Unnecessary use can increase stress on fish and can contribute to medication resistance over time.
How long should I treat with Fix Zole?
Many hobbyists follow daily dosing for 5 to 10 days (do not exceed 10 days). If there is no improvement within 5 days, discontinue treatment and consult an aquatic professional to confirm the cause and next steps.
How quickly might I notice improvement?
Timing depends on the cause, water quality, and overall husbandry. Some hobbyists notice appetite or behavior changes within a few days when the diagnosis is correct and conditions are stable. If fish worsen or do not improve within 5 days, stop treatment and seek help to confirm the diagnosis.
Is Fix Zole safe in saltwater tanks?
Dosing is based on water volume, so metronidazole can be used in freshwater or saltwater treatment tanks when used as directed. Treating in a hospital tank is often preferred for easier monitoring and to reduce risk to sensitive animals in the display system.
Is Fix Zole reef-safe or safe with shrimp and snails?
Sensitivity varies by species and system. Whenever possible, treat fish in a separate hospital tank instead of dosing a display aquarium that contains shrimp, snails, corals, or other invertebrates.
Will metronidazole affect beneficial bacteria in my aquarium?
Metronidazole is primarily selected for protozoa and anaerobic-sensitive targets, but any medication course in a main tank can still stress the system. Use a hospital tank when you can, keep strong aeration, and monitor ammonia and nitrite during treatment.
Can I combine Fix Zole with other medications?
Avoid mixing medications unless advised by an aquatic or avian professional. Remove activated carbon and other chemical filtration media during treatment, turn off UV sterilizers, maintain strong aeration, and monitor ammonia and nitrite.
What precautions should I take after treatment?
After the course, perform a partial water change, then reintroduce activated carbon if you normally use it. Continue monitoring water parameters and only reintroduce sensitive animals (such as invertebrates) once the system is stable.
How do I administer metronidazole to pet birds?
Only administer metronidazole to non-food pet birds under avian veterinary guidance. Your vet should confirm the diagnosis and provide the correct mg-per-kg dose, frequency, and duration. Never guess bird dosages or add tablets to communal drinking water without professional direction.
Is this the same metronidazole humans use?
It shares the same active ingredient name, but Fix Zole is intended for ornamental aquarium fish and non-food pet birds only. Never use it as a substitute for human medicine.
How should I store and dispose of leftover tablets?
Store tablets in the original container in a cool, dry place away from heat and moisture, and keep out of reach of children and pets. Follow local guidance for medication disposal and avoid flushing tablets unless your local authority specifically instructs it.
More Fish & Bird Antibiotics
Need another aquarium fish or pet bird antibiotic? Explore our Fish & Bird Antibiotics Collection for more Fix line and related treatments.
Looking for dosing and water-care advice? Visit the Fish & Bird Antibiotics Blog for practical guides and treatment tips.
