Fish Mox Amoxicillin 250mg & 500mg | Fish Antibiotic
Regular price $24.99 Save $-24.99Fish Mox Amoxicillin 250mg & 500mg | Fish Antibiotic
Fish Mox (Fix Mox) is a fish amoxicillin treatment in 250 mg and 500 mg capsules for ornamental aquarium fish and non-food pet birds.
In freshwater and saltwater tanks it is used for common bacterial problems including dropsy or body swelling, fin and tail rot, columnaris, hemorrhagic septicemia, red streaks, gill disease, swim bladder infections, abscesses, and skin ulcers.
With an avian veterinarian's guidance, the same capsules can be part of an amoxicillin plan for problems such as crop infections and salmonella or paratyphoid in pigeons and other pet birds.
Fix Mox gives you a 250 mg or 500 mg strength, so you can match it to the job: a small hospital tank, a larger community aquarium, or, with veterinary input, a loft or aviary.
It is the current replacement for the discontinued Thomas Labs Fish Mox, also known as fishmox. The 250 mg option stands in for the original strength, and the 500 mg option covers what aquarists knew as Fish Mox Forte and Aqua Mox.
Stock ships from our United States warehouse with fresh expiration dates and clearly printed strengths.
Start treatment early, at the first signs of bacterial stress. Those signs differ between fish and birds, so use the lists below to know what to watch for.
Fish-Specific Symptoms
- Fin and tail rot, including frayed or rotting fins
- Dropsy or body swelling
- Pop-eye or bulging eyes
- Red streaks or open sores on the body
- Skin ulcers and abscesses
- Columnaris and gill disease
- Lethargy, rapid breathing, or appetite loss
Bird-Specific Symptoms Under Veterinary Guidance
- Crop infections
- Suspected salmonella or paratyphoid
- Fluffed-up feathers, lethargy, or inactivity
- Decreased appetite
- Loose or changed droppings
- Labored or difficult breathing
For birds, only use Fix Mox when an avian veterinarian has recommended amoxicillin for a specific problem. Catching an infection early, paired with clean water and good housing, gives your fish and birds the best chance to recover.
Order online and enjoy same-day dispatch on orders placed before 1:30 p.m. CT, Monday through Friday. Fix Mox ships directly from our United States warehouse via USPS or UPS.
Fish Mox vs Fix Mox: What Changed?
If you used to buy Fish Mox, Fish Mox Forte, or Aqua Mox, those brands are now discontinued or hard to find. Fix Mox from Aqua Soma Labs uses the same amoxicillin at the same strengths and steps in as a direct replacement for aquarium use.
Same Amoxicillin Inside
Fish Mox and Fix Mox both contain amoxicillin at 250 mg or 500 mg per capsule, the strengths aquarists have relied on for years.
Updated Labeling & Packaging
Fix Mox carries clear, modern labeling, with usage guidance, amoxicillin strength, and storage notes printed on the bottle.
Same Capsule Form
Pull-apart capsules dissolve in tank water, matching the format aquarists knew from Thomas Labs Fish Mox or Aqua Mox.
Fresh Stock & Current Expiration Dates
Every bottle ships with recent production and clearly printed expiration dates.
Benefits of Fix Mox for Fish & Birds
Covers Common Fish Infections
As an aquarium antibacterial treatment, amoxicillin is used against many of the bacteria behind dropsy, fin and tail rot, red streaks, gill disease, swim bladder infections, and skin ulcers in freshwater and saltwater tanks.
Handles External and Internal Problems
Use it for outward signs such as frayed fins, open sores, or red patches, and for internal infections such as hemorrhagic septicemia that bring swelling, lethargy, or appetite loss. Treat affected fish in a hospital tank.
Flexible 250 mg and 500 mg Strengths
Amoxicillin in a 500 mg or 250 mg capsule lets you scale from a small quarantine tank to a larger system. A common guide is 250 mg per 10 gallons or 500 mg per 20 gallons.
Keep a Bottle on Hand
Bacterial problems move quickly, so keeping Fix Mox stored properly means it is available at the first sign of a bacterial problem in your aquarium.
Easy to Prepare for Fish and Vet-Directed Birds
The capsules pull apart, and the contents dissolve in tank water. Under avian veterinary guidance, the contents may be mixed into soft food or water for birds with specific bacterial problems.
Built for Hospital and Quarantine Tanks
A separate treatment tank lets you remove carbon and UV, maintain stable water quality, and watch sick fish without treating healthy tank mates or sensitive invertebrates.
A Modern Swap for Discontinued Brands
When older Thomas Labs Fish Mox or Aqua Mox products are unavailable, Fix Mox provides a modern replacement with clear strength labels and fresh stock.
Usage Guidelines & Instructions
Set Up a Separate Treatment Area
Move sick fish to a dedicated hospital or quarantine tank before you dose. Take out activated carbon and switch off UV sterilizers, since both can remove amoxicillin from the water.
A 20% to 25% water change before the first dose lowers stress and starts treatment with cleaner water.
Directions for Fish Aquariums
Follow the label guide of 250 mg amoxicillin per 10 gallons or 38 litres, or 500 mg per 20 gallons or 76 litres.
Open the capsule, stir the powder into a cup of tank water, then pour it evenly around the treatment tank.
Repeat every 24 hours for 5 to 10 days, with a partial water change between doses. If nothing improves after about five days, or fish look worse, stop and ask an aquatic veterinarian.
Use in Pet Birds Under Veterinary Guidance
Use Fix Mox in pigeons and other non-food pet birds only when an avian veterinarian directs it.
The veterinarian sets the correct amount for the bird's weight, how often to give it, and how long to continue.
Capsules may be opened into soft food or drinking water so the bird receives the full intended amount, but follow the veterinarian's exact instructions rather than estimating.
Maintain Water Quality and Finish the Treatment
During treatment, monitor ammonia, nitrite, temperature, and aeration.
Finish the full treatment unless a veterinarian says otherwise. Stopping too early may allow symptoms to return.
Afterward, perform a partial water change and restore activated carbon to help remove remaining amoxicillin.
Fix Mox Amounts by Aquarium Size
| Tank volume | Amoxicillin per use | 250 mg capsules | 500 mg capsules |
|---|---|---|---|
| 10 gallons (38 L) | 250 mg | 1 capsule | Not applicable |
| 20 gallons (76 L) | 500 mg | 2 capsules | 1 capsule |
| 30 gallons (114 L) | 750 mg | 3 capsules | 1 capsule plus one 250 mg capsule |
| 40 gallons (151 L) | 1,000 mg | 4 capsules | 2 capsules |
| 55 gallons (208 L) | Approximately 1,375 mg | 5 to 6 capsules | Approximately 3 capsules |
What to Expect During Treatment
Days 1 to 2
Fish may hide or eat less, and the water may appear slightly cloudy. Keep dosing on schedule and maintain strong aeration.
Days 3 to 5
Look for sores or red patches that stop spreading, returning appetite, and steadier breathing. If there is no change by day five, or fish look worse, seek aquatic veterinary advice.
Days 5 to 10
Even when fish improve, complete the recommended treatment. After treatment, perform a partial water change and restore activated carbon.
What You Need for Treatment
A little preparation before the first dose saves trouble later.
- A separate hospital or quarantine tank so the full display aquarium is not treated
- A heater and air stone or sponge filter for stable temperature and strong aeration
- An ammonia and nitrite test kit for monitoring water quality
- A dechlorinator for water changes between doses
- A small net and clean cup for transferring fish and preparing each dose
Pro Tip: Treat sick fish in a separate hospital tank rather than the main display whenever possible. This protects the main biological filter and sensitive invertebrates while concentrating the treatment where it is needed.
How Fix Mox Works
Each Fix Mox capsule contains amoxicillin trihydrate at a strength of 250 mg or 500 mg.
Amoxicillin is an antibacterial used against many Gram-positive and some Gram-negative bacteria, including bacteria associated with fin and tail rot, skin ulcers, red streaks, and certain gill infections in ornamental fish.
Alongside the amoxicillin, each capsule contains standard ingredients that hold the capsule contents together and help them disperse properly in aquarium water or, for birds under veterinary guidance, in soft food.
Safety and Tank Notes
When used at the correct amount, Fix Mox usually causes no problems for ornamental fish or pet birds. The risk of side effects increases with excessive amounts, unnecessarily prolonged treatment, or use in an already severely stressed animal.
Unnecessary or repeated use can also contribute to antibacterial resistance.
Fish
Amoxicillin may cause temporary hiding, mild water cloudiness, or reduced appetite during treatment.
If a fish shows rapid gill movement, loss of balance, surface gasping, or remains on the bottom, stop treatment, improve aeration, add clean dechlorinated water, and contact an aquatic veterinarian.
Birds
When mixed into food or drinking water, amoxicillin may cause reduced appetite, loose or changed droppings, or lethargy, especially if the amount is too high or the bird is sensitive.
A fluffed-up or inactive bird, or one that has difficulty breathing or stops eating, should stop treatment and receive avian veterinary attention.
Invertebrates
Do not use Fix Mox in display tanks containing shrimp, snails, or other sensitive invertebrates.
Move affected fish to a separate hospital or quarantine tank whenever possible.
Safe Use in Your System
Remove activated carbon and switch off UV sterilization during treatment. Monitor ammonia, nitrite, temperature, and oxygen levels.
Do not combine Fix Mox with other treatments unless a veterinarian specifically advises it.
Important Safety & Storage Information
Fix Mox is for aquarium and ornamental fish and non-food pet birds only. It is not for animals raised for food.
If you are sensitive to penicillins, avoid direct contact with the capsule contents. Wash your hands after handling and wear suitable gloves when needed.
Store the capsules in their original container in a cool, dry location at 59–86°F or 15–30°C. Protect them from moisture and direct sunlight, keep the lid closed, and store out of reach of children and animals.
Shipping & Returns
Shipping Policy
Orders ship from our United States warehouse within one business day through USPS or UPS. Rates and estimated delivery times are calculated at checkout.
For complete shipping details, review our shipping policy.
Review Shipping Policy →Refund Policy
If there is an issue with your order, eligible products may be returned or exchanged within 30 days according to our store guidelines.
Review the complete refund policy before sending a product back.
Review Refund Policy →Frequently Asked Questions
What is Fix Mox used for in fish and birds?
Fix Mox contains amoxicillin and is intended for certain bacterial problems in ornamental fish. These may include fin and tail rot, dropsy, red streaks, ulcers, abscesses, columnaris, septicemia, and certain gill infections.
For non-food pet birds, use should only occur under the guidance of an avian veterinarian.
Is Fix Mox the same as Fish Mox or Aqua Mox?
Fix Mox is presented as the current Aqua Soma Labs replacement for discontinued Fish Mox, Fish Mox Forte, and Aqua Mox products. It is available in the familiar 250 mg and 500 mg amoxicillin capsule strengths.
Is Fix Mox, also called fish mox, the same as amoxicillin?
The active ingredient in Fix Mox is amoxicillin trihydrate. Each capsule is clearly labeled as containing either 250 mg or 500 mg.
Is Fix Mox the same as fish amoxicillin 500 mg?
The 500 mg Fix Mox option contains 500 mg of amoxicillin per capsule. A separate 250 mg strength is also available.
Where can I buy Fish Mox amoxicillin online?
Fix Mox capsules can be ordered through this online store and shipped from our United States warehouse according to the current shipping terms.
Can Fix Mox be used for dogs or cats?
No. This product is labeled for ornamental aquarium fish and non-food pet birds. It is not intended for dogs, cats, humans, or food-producing animals.
What is the difference between Fish Mox and Fish Mox Forte?
The traditional Fish Mox product used the 250 mg strength, while Fish Mox Forte referred to the stronger 500 mg capsule. Fix Mox is available in both 250 mg and 500 mg strengths.
How do I know if my fish might need a fish amoxicillin treatment?
Possible bacterial signs include frayed or rotting fins, swelling, red streaks, sores, ulcers, bulging eyes, abnormal breathing, lethargy, or appetite loss.
Similar signs can also result from poor water quality, parasites, fungal problems, or other conditions, so professional assessment is recommended when the cause is uncertain.
Can I use Fix Mox in my main community or reef tank?
A separate hospital or quarantine tank is preferred. This reduces exposure of healthy tank mates and sensitive invertebrates and helps protect the main aquarium's biological filtration.
How much Fix Mox should I use per gallon?
The supplied label-style reference is 250 mg per 10 gallons, which is approximately 25 mg per gallon. Follow the current bottle label rather than relying only on a general calculation.
How long should I treat with Fix Mox?
The supplied instructions describe treatment every 24 hours for approximately 5 to 10 days, with partial water changes between doses. Always follow the current product label.
Does Fix Mox work in saltwater aquariums?
Fix Mox is presented for ornamental fish in freshwater and saltwater treatment systems. A separate hospital tank is recommended, especially for marine aquariums containing invertebrates.
Is Fix Mox safe for pet birds, and can I treat more than one bird?
Use in non-food pet birds should only occur under avian veterinary guidance. The correct amount depends on the species, body weight, condition, administration method, and number of birds being treated.
Will Fix Mox affect beneficial bacteria in my aquarium?
Antibacterial treatments may interfere with beneficial biological filtration. Use a separate treatment tank and monitor ammonia and nitrite closely.
Can Fix Mox treat fungal, viral, or parasitic infections?
Fix Mox contains an antibacterial ingredient. It should not be assumed to treat fungal, viral, or parasitic conditions unless a qualified professional has identified an appropriate reason for its use.
Can I combine Fix Mox with other treatments?
Do not combine Fix Mox with other aquarium or bird treatments unless a veterinarian specifically recommends the combination.
What is the active ingredient in Fish Mox?
The active ingredient is amoxicillin trihydrate, supplied as either 250 mg or 500 mg per capsule.
How should I store Fix Mox capsules?
Keep the capsules in their original, tightly closed container at 59–86°F or 15–30°C. Protect the bottle from moisture, excessive heat, and direct sunlight, and keep it away from children and animals.
What should I do if my fish are not improving on Fix Mox?
Stop treatment and seek aquatic veterinary advice if the fish become worse or show no improvement after the period specified on the product label.
What is fish mox?
Fish Mox is a commonly used name for amoxicillin capsules labeled for ornamental aquarium fish. Fix Mox is the current Aqua Soma Labs product offered in 250 mg and 500 mg capsule strengths.
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