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Fish Sulfa Forte (Fix Sulfa) Tablets, 960 mg
Fix Sulfa at a Glance
For
Ornamental aquarium fish in freshwater and saltwater systems
Helps with
Fin and tail rot, ulcers, columnaris, pop-eye, and other bacterial signs
Form
Scored tablets, 960 mg each
Count sizes
30-count and 60-count bottles
Water type
Freshwater and saltwater
Made in
United States by Aqua Soma Labs
Fish Sulfa (Fix Sulfa) SMZ/TMP 960 mg is an antibacterial treatment for ornamental aquarium fish.
Each scored tablet combines sulfamethoxazole 800 mg with trimethoprim 160 mg. Aquarium keepers use this dual-ingredient combination to help manage suspected bacterial problems in freshwater and saltwater treatment systems.
In older aquarium listings and hobby forums, this SMZ/TMP product may also be called Fish Sulfa, Fish Sulfa Forte, FISHBIOTIC SMZ/TMP, Aqua Sulfa, or Aqua-SMZ/TMP.
Fix Sulfa is the current-production Aqua Soma Labs replacement for the discontinued Thomas Labs Fish Sulfa Forte.
Aquarium keepers commonly use this combination when fish show symptoms associated with fin and tail rot, columnaris or cotton-wool-type patches, skin sores, ulcer-like lesions, bacterial hemorrhagic septicemia, pop-eye, cloudy eyes, and body-slime concerns.
These signs may involve susceptible bacteria such as Aeromonas, Vibrio, or Streptococcus.
SMZ/TMP combines two active ingredients that work together to help slow the growth of certain bacteria.
Used as directed, sulfamethoxazole and trimethoprim work best alongside stable water parameters, strong aeration, clean treatment water, reduced stress, and appropriate aquarium husbandry.
Fix Sulfa comes as a consistent 960 mg scored tablet that can be divided, crushed, and dissolved.
It is available in bottles containing 30 or 60 tablets with clearly printed expiration dates, allowing aquarium keepers to choose a suitable quantity for one quarantine tank or a multi-tank fish room.
Begin treatment at the first signs of bacterial stress and use a hospital or quarantine tank whenever practical.
Fish Symptoms Aquarists Treat With Fix Sulfa
Fin and tail rot with frayed or deteriorating fins
Skin sores, ulcer-like lesions, and red streaks
Pop-eye or bulging eyes
Cloudy eyes
Columnaris with a cotton-wool-type appearance
Bacterial hemorrhagic septicemia
Body-slime concerns associated with susceptible bacteria
Lethargy, rapid breathing, or appetite loss that does not resolve after water-quality correction
Same-day dispatch: Qualifying orders placed before 1:30 p.m. CT, Monday through Friday, ship from our United States warehouse through USPS or UPS.
Important Notice: This product is intended for aquarium and ornamental fish only. It is not intended for animals raised for food.
Fish Sulfa Forte vs Fix Sulfa: What Changed?
If you previously purchased Thomas Labs Fish Sulfa Forte, FISHBIOTIC SMZ/TMP, Aqua Sulfa, or Aqua-SMZ/TMP, here is what has changed and what remains the same.
Active ingredients
Same SMZ/TMP Combination
Fix Sulfa contains sulfamethoxazole 800 mg and trimethoprim 160 mg per tablet, providing a combined strength of 960 mg.
Branding
Updated Fix Branding
Aqua Soma Labs produces Fix Sulfa as the current replacement for discontinued Fish Sulfa Forte and other older aquarium SMZ/TMP products.
Tablet format
Same Scored Tablet Form
Each tablet provides a consistent 960 mg total strength and can be divided, crushed, and dissolved according to the aquarium-water volume.
Bottle options
Flexible Bottle Sizes
Choose between 30-count and 60-count bottles for short treatment plans, quarantine systems, or larger multi-tank setups.
Benefits of Fix Sulfa for Fish
01
Dual-Action SMZ/TMP Combination
Fix Sulfa pairs sulfamethoxazole and trimethoprim, a combination aquarium keepers use to help manage certain bacterial concerns in ornamental fish.
02
Made in the United States
Fix Sulfa is manufactured in the United States by Aqua Soma Labs as the current-production replacement for discontinued Fish Sulfa Forte products.
03
Support for Common Aquarium Problems
Aquarium keepers may choose Fish Sulfa tablets for fin and tail rot, columnaris-type patches, cotton-wool-type signs, ulcers, pop-eye, cloudy eyes, and persistent bacterial symptoms.
04
External and Internal Bacterial Signs
SMZ/TMP may be used in a hospital tank for visible sores and fin damage or when lethargy and appetite loss occur together with suspected bacterial stress.
05
Consistent 960 mg Tablet Strength
Each scored tablet provides a predictable amount of sulfamethoxazole and trimethoprim, helping aquarium keepers plan repeatable amounts for different water volumes.
06
Intended for Ornamental Fish
Fix Sulfa is formulated and labeled for ornamental aquarium fish and provides a countable tablet format for treatment-tank use.
07
Helpful for Hospital Tanks
A separate hospital or quarantine tank allows closer observation, more accurate treatment, and reduced exposure of healthy tank mates.
Usage Guidelines & Instructions
These steps follow the supplied Fix Sulfa 960 bottle-label directions for SMZ/TMP use in ornamental aquarium fish.
Quick Usage Summary
Dissolve one tablet and add it for every 40 gallons or approximately 151 litres of treatment water.
Repeat every 24 hours with a partial water change between treatments for 5 to 10 days.
Discontinue use if no improvement is noted after five days.
Before You Dose
1
Measure the Actual Water Volume
Calculate the real volume of water being treated rather than relying only on the aquarium's advertised capacity.
Account for substrate, rocks, decorations, equipment, and the actual fill level.
2
Use a Hospital or Quarantine Tank
Treat affected fish in a separate system whenever practical for better control and closer observation.
3
Remove Carbon and Turn Off UV
Remove activated carbon and other chemical filtration media before treatment.
Switch off ultraviolet sterilization because these systems may reduce treatment availability in the water.
4
Increase Aeration
Increase surface agitation and aeration while keeping the treatment-tank temperature stable.
Directions for Use
1
Dissolve and Add the Treatment
Fully dissolve one tablet in a small cup of aquarium water.
Add the dissolved mixture evenly throughout the treatment tank at a rate of one tablet per 40 gallons or approximately 151 litres.
2
Repeat Every 24 Hours
Repeat treatment once every 24 hours.
Perform a partial water change between treatments to maintain suitable water quality.
3
Complete Treatment and Monitor Progress
Continue treatment for 5 to 10 days according to the current bottle label.
Monitor appetite, swimming behavior, breathing, fin condition, sores, and signs of stress.
Discontinue use if no improvement is noted after five days.
If fish appear worse or develop severe stress, stop treatment and seek aquatic veterinary advice.
4
Post-Treatment Cleanup
After treatment is complete, perform a partial water change and resume normal filtration.
Replace activated carbon or other chemical media if they were removed.
Continue monitoring ammonia, nitrite, temperature, and fish behavior for several days.
Fix Sulfa Amounts by Aquarium Size
Tank volume
Fix Sulfa 960 amount
How to measure
10 gallons (38 L)
ยผ tablet
Divide the scored tablet or add one-quarter of a fully dissolved tablet
20 gallons (76 L)
ยฝ tablet
Divide the scored tablet or add one-half of a fully dissolved tablet
40 gallons (151 L)
1 tablet
Dissolve one complete tablet according to the label standard
80 gallons (303 L)
2 tablets
Dissolve two complete tablets
120 gallons (454 L)
3 tablets
Dissolve three complete tablets
The supplied Fix Sulfa 960 label states one tablet per 40 gallons or approximately 151 litres, which equals about 24 mg of combined sulfamethoxazole and trimethoprim per gallon. The 40-gallon row is the exact label instruction, while the other rows scale that same rate. Dose according to actual treatment-water volume, not the number of fish. The current bottle label or an aquatic veterinarian's directions take priority over this quick-reference chart.
What to Expect During Treatment
Days 1 to 2
Fish may hide, eat less, or produce slightly cloudy treatment water. Maintain the treatment schedule and keep aeration strong.
Days 3 to 5
Look for sores and red patches that stop spreading, returning appetite, improved activity, and steadier breathing.
Days 5 to 10
Complete the recommended treatment period. After treatment, perform a partial water change and restore activated carbon if normally used.
If no improvement is seen by day five, or if symptoms become worse, discontinue treatment and seek aquatic veterinary guidance.
What You Need for Treatment
A separate hospital or quarantine tank
A suitable aquarium heater
An air stone or established sponge filter
An ammonia and nitrite test kit
A suitable water conditioner or dechlorinator
A small net for gentle transfer
A clean cup for dissolving and measuring the treatment
Pro Tip: Hospital-tank treatment helps protect the display aquarium, keeps the amount consistent, and makes it easier to maintain ammonia and nitrite at safe levels during recovery.
How Fix Sulfa Works
Each Fix Sulfa tablet combines sulfamethoxazole 800 mg with trimethoprim 160 mg, providing a total SMZ/TMP strength of 960 mg.
When dissolved and added to aquarium water according to the label, the two active ingredients work together to help slow the growth of certain susceptible bacteria.
This combination is commonly used by aquarium keepers for suspected bacterial concerns involving fins, skin, sores, ulcers, eyes, and systemic signs in ornamental freshwater and saltwater fish.
Each tablet also contains standard inactive ingredients that help hold the tablet together, support storage stability, and allow the contents to disperse when dissolved in water.
Safety and Tank Notes
Individual fish may respond differently to treatment. Follow the current label and monitor fish and water quality closely throughout the treatment period.
Possible Side Effects in Fish
Possible temporary reactions include reduced appetite, mild lethargy, hiding behavior, and occasional water cloudiness.
If fish develop rapid gill movement, surface gasping, loss of balance, or remain on the bottom, stop treatment, increase aeration, and seek aquatic veterinary advice.
Stop Treatment If
Stop treatment when fish show severe stress, worsening symptoms, rapid gill movement, surface gasping, loss of balance, or a serious decline in activity.
Increase aeration immediately and consult an aquatic veterinarian if the signs do not stabilize.
Water Quality and Biofilter Awareness
Keep aeration strong and monitor ammonia and nitrite closely.
Perform partial water changes when necessary to keep the treatment system stable.
Filtration During Treatment
Remove activated carbon and other chemical filtration media before treatment.
Switch off ultraviolet sterilization and resume normal filtration only after treatment is complete.
Invertebrates and Display Tanks
If the aquarium contains shrimp, snails, corals, or other sensitive invertebrates, treat affected fish in a separate hospital tank whenever practical.
Do Not Mix Treatments
Avoid combining Fix Sulfa with other aquarium treatments unless the product label explicitly allows it or an aquatic veterinarian recommends it.
Important Warnings & Precautions
Aquarium use only: Fix Sulfa is intended for ornamental aquarium fish only.
Not for food fish: Do not use this product on fish raised for human consumption.
Handling: Avoid contact with the dissolved treatment. Wash your hands after handling and use suitable gloves when needed. Keep the tablet contents and dissolved product away from the skin and eyes.
Storage: Keep the container tightly closed in a cool, dry location protected from direct sunlight and moisture.
Keep out of reach of children and animals. Check the expiration date and do not use expired tablets.
Discontinue if no improvement: If no improvement is noted after five days, stop treatment and re-evaluate the diagnosis or seek aquatic veterinary advice.
Shipping & Returns
Shipping Policy
Orders ship from our United States warehouse within one business day through USPS or UPS.
Qualifying orders placed before 1:30 p.m. CT, Monday through Friday, may ship the same business day.
Shipping rates and estimated delivery times are calculated at checkout.
Fix Sulfa is an SMZ/TMP antibacterial treatment for certain suspected bacterial problems in ornamental aquarium fish, including fin and tail rot, ulcers, columnaris-type signs, pop-eye, cloudy eyes, red streaking, and systemic bacterial stress.
What is Fish Sulfa Forte?
Fish Sulfa Forte was an aquarium SMZ/TMP product containing sulfamethoxazole and trimethoprim. Fix Sulfa is the current Aqua Soma Labs replacement in the same combined 960 mg strength.
What is the difference between Fish Sulfa Forte and Fix Sulfa?
Fix Sulfa uses the same combination of sulfamethoxazole 800 mg and trimethoprim 160 mg associated with older Fish Sulfa Forte products. The main changes are the manufacturer, branding, packaging, and current production.
Is Fix Sulfa a replacement for Aqua-SMZ/TMP?
Fix Sulfa is presented as the current Aqua Soma Labs replacement for older Aqua Sulfa and Aqua-SMZ/TMP aquarium products.
Where can I buy SMZ/TMP fish tablets online?
Fix Sulfa 960 mg tablets can be ordered through this online store in 30-count or 60-count bottles and shipped according to the current store shipping policy.
What are the active ingredients in each tablet?
Each scored tablet contains sulfamethoxazole 800 mg and trimethoprim 160 mg, providing a combined strength of 960 mg.
What is the Fix Sulfa amount for fish?
The supplied label direction is one 960 mg tablet per 40 gallons or approximately 151 litres of treatment water.
How much Fix Sulfa should I use per gallon?
One tablet per 40 gallons equals approximately 24 mg of combined sulfamethoxazole and trimethoprim per gallon. Follow the current bottle label rather than relying only on a calculated per-gallon amount.
How long should I treat with Fix Sulfa?
The supplied instructions describe treatment every 24 hours for 5 to 10 days, with a partial water change between treatments.
Discontinue treatment if no improvement is noted after five days.
How soon should I see improvement?
Improvement may appear within three to five days through sores that stop spreading, improved appetite, steadier breathing, and increased activity.
Stop treatment and seek professional guidance if fish worsen or no improvement appears by day five.
Should I treat in the main tank or a hospital tank?
A separate hospital or quarantine tank is preferred. This provides better treatment control, protects healthy tank mates, and reduces disturbance to the display aquarium.
Do I need to remove carbon or turn off UV?
Remove activated carbon and other chemical filtration media and switch off ultraviolet sterilization during treatment because these systems may reduce treatment availability in the water.
Will Fix Sulfa harm beneficial aquarium bacteria?
Antibacterial treatment may disturb biological filtration. Use a separate treatment system when possible and monitor ammonia and nitrite closely.
Can Fix Sulfa treat fungal, viral, or parasitic infections?
Fix Sulfa is an antibacterial treatment. It should not be expected to treat fungal, viral, or parasitic conditions.
Is Fix Sulfa safe for betta fish and small aquariums?
Small treatment tanks require careful measurement. Because each tablet is scored, it may be divided, or a complete tablet may be dissolved in a measured amount of water and the correct fraction added. Always follow the current bottle label.
Does Fix Sulfa work in saltwater aquariums?
Fix Sulfa is presented for ornamental fish in freshwater and saltwater treatment systems. Use a separate hospital tank when the display aquarium contains corals or sensitive invertebrates.
Can I combine Fix Sulfa with other fish treatments?
Do not combine Fix Sulfa with other treatments unless the label specifically permits the combination or an aquatic veterinarian recommends it.
What if my fish are not improving?
Discontinue treatment if no improvement is noted after five days. Re-evaluate the water quality and diagnosis and seek aquatic veterinary advice.
What should I do after finishing treatment?
Perform a partial water change, resume normal filtration, restore activated carbon or chemical media, and continue monitoring ammonia, nitrite, and fish behavior for several days.
How should I store and dispose of Fix Sulfa tablets?
Store tablets tightly closed in the original container in a cool, dry location protected from sunlight and moisture.
Follow the product label and applicable local requirements when disposing of unused tablets, treatment water, or filter media. Avoid releasing concentrated treatment into natural waterways.
Bottom Line
Fix Sulfa is an SMZ/TMP 960 mg antibacterial treatment containing sulfamethoxazole 800 mg and trimethoprim 160 mg for bacterial concerns in ornamental aquarium fish.
It is the current-production replacement for discontinued Thomas Labs Fish Sulfa Forte.
Dose according to water volume at one tablet per 40 gallons or approximately 151 litres, repeat every 24 hours with a partial water change between treatments, and continue for 5 to 10 days according to the current bottle label.
Reassess treatment at day five and discontinue use if no improvement is noted.
Fix Sulfa does not treat fungal, viral, or parasitic conditions and is intended only for ornamental aquarium fish, not animals raised for food.
Choose the bottle size that fits your aquarium setup, or compare the additional Fix line products below.
More Fish & Bird Treatments
Fix Mox (Amoxicillin) 250/500 mg
A treatment for fin rot, dropsy, ulcers, and other bacterial concerns in ornamental fish. Available in 30-count and 100-count capsules.
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Transparency & Verification
How Product Information Is Verified
Who is responsible for this page: The store editorial team responsible for reviewing and maintaining product information.
Verification snapshot: This page is written from the current product label for this item and reviewed for accuracy and consistency before publishing.
How We Verify Product Information
Label-First Accuracy
Directions, treatment duration, storage information, and warnings are taken from the current product label.
Specification Validation
Active ingredients, tablet strengths, bottle counts, and manufacturer details are cross-checked against available product specifications.
Consistency Checks
Product content is reviewed for consistent directions, strengths, storage information, and safety language throughout the page.
Updates
Pages are updated when product labels, packaging, bottle counts, manufacturer details, or directions change.
What we do not do: We do not invent product claims, and we do not add usage directions beyond what the current product label states for its intended use.
See something that does not match the product you received? Please contact us so the information can be reviewed and updated.
Educational use: This content is provided for general informational purposes only and is not a substitute for advice from a qualified veterinarian.
