Direct from Aqua Soma Labs with extended expiration dates.
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Fix Mox (Fish Mox) Amoxicillin Capsules - Fish & Bird Antibiotic 250 mg / 500 mg
Fix Mox at a Glance
Active Ingredient
Amoxicillin trihydrate
Strength
250 mg / 500 mg per capsule
Form
Capsules
Count Sizes
30 count, 100 count
For
Ornamental aquarium and fish tank use, plus non-food pet birds
Manufacturer
Aqua Soma Labs
Prescription
No vet prescription required (over-the-counter)
Fix Mox (Fish Mox) is an over-the-counter amoxicillin antibiotic in 250 mg and 500 mg capsules for ornamental aquarium fish and non-food pet birds. People also search for it as fish amoxicillin, fish amoxicillin 500mg, fishmox, or by older names like Fish Mox Forte and Aqua Mox. In freshwater and saltwater tanks it treats common bacterial problems: dropsy (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 also be part of an amoxicillin plan for problems such as crop infections and salmonella or paratyphoid in pigeons and other pet birds.
As a fish antibiotic, Fix Mox delivers amoxicillin 500mg for fish or a 250 mg dose, so you can match the strength to the job: a small hospital tank, a larger community aquarium, or, with veterinary input, a loft or aviary. Fix Mox is the current replacement for the discontinued Thomas Labs Fish Mox: the 250 mg option stands in for fish amoxicillin 250mg, and the 500 mg option covers what people search for as fish mox 500mg or fish mox forte 500mg. Stock ships from our U.S. 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.
For birds, only reach for 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 U.S. warehouse via USPS or UPS.
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.
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 Active Ingredient Fish Mox and Fix Mox both contain amoxicillin (250 mg or 500 mg per capsule), the same penicillin-family antibiotic aquarists have long used.
Updated Labeling & Packaging Fix Mox carries clear, modern labeling, with dosing guidance, the active ingredient, and storage notes printed on the bottle.
Same Capsule Format Pull-apart capsules that dissolve in tank water, matching the format people 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 antibiotic for fish tanks, amoxicillin works against many of the bacteria behind dropsy, fin and tail rot, red streaks, gill disease, swim bladder infections, and skin ulcers, in both freshwater and saltwater tanks.
Handles External and Internal Problems
Use it for outward signs like frayed fins, open sores, or red patches, and for internal infections such as hemorrhagic septicemia that bring swelling, lethargy, or loss of appetite. Treat affected fish in a hospital tank.
Flexible 250 mg and 500 mg Strengths
As a fish antibiotic, amoxicillin 500mg or the 250 mg capsule lets dosing scale from a small quarantine tank to a large system. A common guide is 250 mg per 10 gallons or 500 mg per 20 gallons; an aquatic veterinarian can tailor it.
No Vet Prescription Required
Fix Mox sells over the counter, so you can get amoxicillin for fish without a vet prescription and buy fish amoxicillin online with no prescription required to order. Keep a bottle on hand so you can act at the first sign of infection in your aquarium.
Easy to Dose for Fish and Vet-Directed Birds
The capsules pull apart, and the contents dissolve fast in tank water so the dose reaches even shy or hiding fish. Under avian veterinary guidance, the same contents mix into soft food or water for birds with problems like crop infections.
Built for Hospital and Quarantine Tanks
Fix Mox does its best work in a separate hospital or quarantine tank. There you can pull carbon and UV, hold water quality steady, and watch the sick fish without dosing healthy tank mates or sensitive invertebrates.
A Modern Swap for Discontinued Brands
When the old Thomas Labs Fish Mox or Aqua Mox is unavailable, Fix Mox is the go-to replacement. Clear strength labels and fresh stock make it easy to match the dose to your tank or a vet-directed bird plan.
Dosage Guidelines & Instructions
Directions for Use:
Set Up a Separate Treatment Area
Move sick fish to a dedicated hospital or quarantine tank before you dose. Take out the activated carbon and switch off UV sterilizers, since both pull amoxicillin from the water. A 20-25% water change before the first dose lowers stress and starts treatment on cleaner water.
Dose for Fish Aquariums
Follow the label guide of 250 mg amoxicillin per 10 gallons (38 L) or 500 mg per 20 gallons (76 L). 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 5-10 days, with a partial water change between doses. If nothing improves after about 5 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 vet sets the mg-per-kg dose, how often to give it, and how long to continue. Capsules are usually opened into soft food or drinking water so the bird takes the full dose, but follow the vet's exact instructions rather than guessing.
Maintain Water Quality & Finish the Course
Through treatment, keep an eye on ammonia, nitrite, and temperature, and keep aeration strong. Finish the full course unless a veterinarian says otherwise; stopping early lets symptoms come back. Afterward, run a partial water change and put activated carbon back in to clear out leftover medication and help the tank settle.
Fix Mox Dosing by Aquarium Size
Tank volume
Amoxicillin per dose
250 mg capsules
500 mg capsules
10 gallons (38 L)
250 mg
1
—
20 gallons (76 L)
500 mg
2
1
30 gallons (114 L)
750 mg
3
1 + one 250 mg
40 gallons (151 L)
1000 mg
4
2
55 gallons (208 L)
about 1375 mg
5 to 6
3
These figures come from the label-style guideline of 250 mg per 10 gallons, roughly 25 mg per gallon. Dose by the water volume of your treatment tank, not by the number of fish, give one dose every 24 hours for 5 to 10 days, and round to the nearest practical capsule. The bottle label or your aquatic veterinarian takes priority over this quick-reference chart.
What to Expect During Treatment
Days 1 to 2
Fish may hide or eat less, and the water can look slightly cloudy. This is normal early on. Keep dosing on schedule and keep aeration strong.
Days 3 to 5
Look for signs it is working: sores and red patches stop spreading, appetite starts to return, and breathing steadies. If there is no change by day 5, or the fish look worse, stop and ask an aquatic veterinarian.
Days 5 to 10
Even if the fish are improving, finish the full course so the infection does not return. Afterward, run a partial water change and put activated carbon back in to clear any leftover medication.
What You Need for a Treatment Course
A little setup before the first dose saves trouble later.
A separate hospital or quarantine tank, so you are not medicating the whole display.
A heater and an air stone or sponge filter for steady temperature and strong aeration.
An ammonia and nitrite test kit to keep tabs on water quality.
A dechlorinator for the water changes between doses.
A small net and a clean cup for gentle transfer and measuring the dose.
Pro Tip: Treat sick fish in a separate hospital tank rather than the main display whenever you can. It keeps your display biofilter and invertebrates safe while you focus the medication where it is needed.
What Makes This Antibiotic Effective?
Active Ingredient: Amoxicillin Trihydrate (250 mg or 500 mg per capsule)
Amoxicillin is a penicillin-family beta-lactam. It attacks the cell wall that bacteria need to grow, which stops many Gram-positive and some Gram-negative bacteria, the kind behind fin and tail rot, skin ulcers, red streaks, and certain gill infections in ornamental fish.
Inactive Ingredients
Each capsule also holds standard pharmaceutical fillers. They keep the amoxicillin stable on the shelf and let the contents disperse properly in aquarium water, or in soft food for birds under veterinary guidance.
Side Effects & Safety Tips
Most fish and pet birds tolerate Fix Mox well at the right dose. As with any penicillin-class antibiotic, the risk of side effects climbs with overdosing, long courses, or treating an already stressed animal, and overuse feeds resistance.
Fish
Amoxicillin can cause short-term hiding, mild water cloudiness, and lower appetite during treatment. If a fish shows real distress, rapid gill movement, loss of balance, gasping at the surface, or lying on the bottom, stop, add clean dechlorinated water for better aeration, and call an aquatic veterinarian.
Birds
Mixed into food or water, amoxicillin may cause reduced appetite, loose or changed droppings, and lethargy, especially at too high a dose or in a sensitive bird. A fluffed-up, inactive bird, or one that struggles to breathe or stops eating, should come off the drug and see an avian veterinarian right away.
Invertebrates
Do not use Fix Mox in display tanks with shrimp, snails, or other invertebrates; strong antibiotics can harm them and upset the tank. Move affected fish to a separate hospital or quarantine tank instead.
Safe use in your system
Treat in a hospital or quarantine tank where you can, pull activated carbon and switch off UV during treatment, and keep an eye on ammonia, nitrite, and temperature. Do not combine Fix Mox with other antibiotics or medications unless a veterinarian advises it.
Important safety & storage
Fix Mox is for aquarium and ornamental fish and non-food pet birds only. It is not for human use and not for animals raised for food. Anyone sensitive to penicillins should avoid contact with the capsule contents; wash your hands after handling, and wear gloves if needed. Store the capsules in their original container in a cool, dry place at 59-86°F (15-30°C), out of moisture, sunlight, and reach of children and pets, with the lid closed.
Shipping & Returns
Shipping Policy: Orders ship from our U.S. warehouse within 1 business day via USPS or UPS, with rates and delivery times calculated at checkout. For full shipping details, please review our shipping policy.
Refund Policy: If there is an issue with your order, you may be able to return or exchange items within 30 days according to our store guidelines. Before sending anything back, please review our refund policy carefully.
Frequently Asked Questions
What is Fix Mox used for in fish and birds?
Fix Mox is amoxicillin in 250 mg and 500 mg capsules, sometimes written as fishmox. Aquarists use it for bacterial problems like dropsy (body swelling), fin and tail rot, red streaks, pop-eye, skin ulcers, and some gill infections. For non-food pet birds, it supports a veterinarian-directed plan for selected bacterial issues.
Is Fix Mox the same as Fish Mox or Aqua Mox?
It is the same idea under a current label. Fish Mox, Fish Mox Forte, and Aqua Mox were earlier amoxicillin products for aquarium use, and Fix Mox carries the same active ingredient for the same problems. Follow the Fix Mox label for the dose and duration.
Is Fix Mox (fish mox) the same as amoxicillin?
The active ingredient is amoxicillin trihydrate, the same penicillin-family antibiotic, at 250 mg and 500 mg per capsule. What differs is the labeling: Fix Mox is made and sold only for ornamental aquarium fish and non-food pet birds, not for people or for animals raised for food.
Is Fix Mox the same as fish amoxicillin 500mg?
In the 500mg option, yes. That capsule holds 500 mg of amoxicillin, the strength people search for as fish amoxicillin 500mg. The 250mg option holds 250 mg. Same ingredient, same pull-apart capsule, so you pick the strength that fits your tank size or a vet-directed bird plan.
Can I buy fish amoxicillin (Fix Mox) without a vet prescription?
You can. Fix Mox is an over-the-counter fish antibiotic, so you can buy fish amoxicillin online without a vet prescription, and no prescription is required to order. For severe or repeat infections, or before treating pet birds, a veterinarian's diagnosis is still the safer route.
Where can I buy Fish Mox (amoxicillin) online?
If you are wondering where can I buy fish mox, you can order Fix Mox, the current Fish Mox replacement, directly from Fine Pet Health. Orders leave our U.S. warehouse within one business day by USPS or UPS, with clear labels and current expiration dates.
No. The label covers ornamental aquarium fish and non-food pet birds only, not dogs, cats, or other mammals. A dog or cat that needs amoxicillin should get a vet-prescribed, species-specific medication and dose.
What is the difference between Fish Mox and Fish Mox Forte?
It comes down to strength. The original Thomas Labs Fish Mox was 250 mg per capsule, while Fish Mox Forte was 500 mg. Fix Mox covers both: choose the 250mg option, the fish mox 250mg equivalent, for standard strength, or the 500mg option for the Forte equivalent. The ingredient and capsule format are the same either way.
How do I know if my fish might need a fish amoxicillin antibiotic?
Look for frayed or rotting fins, red or white ulcers, red streaks in the fins or body, bulging eyes (pop-eye), labored breathing, or listless behavior that good water quality does not fix. A fish veterinarian or experienced aquarist can confirm whether the cause is bacterial and whether amoxicillin fits.
Can I use Fix Mox in my main community or reef tank?
Better not. Treat sick fish in a separate hospital or quarantine tank. Amoxicillin is not meant for reef tanks or setups with shrimp, snails, corals, or other invertebrates, where it can harm them or knock back the beneficial filter bacteria.
How much Fix Mox should I use per gallon?
The label guide is 250 mg amoxicillin per 10 gallons (38 L) or 500 mg per 20 gallons (76 L). Open the capsule, mix the powder into a cup of tank water, and spread it around the treatment tank. Repeat every 24 hours for 5-10 days, with a partial water change between doses. Measure the tank volume first.
How long should I treat with Fix Mox?
For fish, most courses run 5-10 days, dosing once every 24 hours at roughly 250 mg per 10 gallons (38 L) or 500 mg per 20 gallons (76 L), or as an aquatic veterinarian advises. For birds, the dose and length come from the avian vet, not from the label.
Does Fix Mox work in saltwater aquariums?
Yes. It works against susceptible bacteria in both freshwater and saltwater tanks. Treat in a hospital or quarantine tank where you can, to protect the biofilter and any invertebrates in the display.
Is Fix Mox safe for pet birds, and can I treat more than one bird?
Only under an avian veterinarian's direction. The vet works out the mg-per-kg dose and decides whether to treat one bird or a whole loft or flock. Do not guess avian doses or add capsule contents to shared water on your own.
Will Fix Mox affect beneficial bacteria in my aquarium?
It can, if you dose the main tank. Amoxicillin does not tell good bacteria from bad. A hospital tank, regular ammonia and nitrite checks, and partial water changes during and after treatment keep the biofilter protected.
Can Fix Mox treat fungal, viral or parasitic infections?
No. Amoxicillin targets certain bacteria only. It does nothing for fungi, viruses, or parasites like ich, flukes, or worms, which need different medications chosen with help from an aquatic or avian veterinarian.
Can I combine Fix Mox with other medications?
Avoid it unless a veterinarian says otherwise. Stacking antibiotics or other treatments can stress fish, shift water chemistry, and hide which product is helping or causing trouble. If a second medication is needed, finish the amoxicillin course first.
What is the active ingredient in Fish Mox?
Amoxicillin trihydrate, a penicillin-family antibiotic. Each Fix Mox capsule holds 250 mg or 500 mg, the same ingredient used in the old Thomas Labs Fish Mox and Aqua Mox products for ornamental aquarium fish.
How should I store Fix Mox capsules?
Keep the capsules in their original container in a cool, dry spot at 59-86°F (15-30°C), out of moisture and sunlight, and away from children and pets, with the lid closed. Check the expiration date and do not use capsules past it.
What should I do if my fish are not improving on Fix Mox?
Stop after about 5 days if there is no change, or sooner if the fish get worse, then improve water quality and aeration and ask an aquatic veterinarian. No response can mean the cause is not bacterial, the bacteria do not respond to amoxicillin, or the dose or length was off.
What is fish mox?
Fish mox is a common name for amoxicillin sold as an aquarium antibiotic. Fix Mox is the current version: among fish antibiotics, amoxicillin 500mg and 250mg capsules for ornamental fish and non-food pet birds. It treats bacterial problems like fin rot, dropsy, red streaks, and skin ulcers, not fungi, viruses, or parasites.
Can I use Fix Mox as an antibiotic in a fish tank or aquarium?
Yes, that is its purpose. Fix Mox is an amoxicillin for fish tanks and aquariums, dosed by water volume rather than by fish. A common guide is 250 mg per 10 gallons or 500 mg per 20 gallons. Dose in a hospital or quarantine tank where you can, to spare the biofilter and any invertebrates in the display.
More Fish & Bird Antibiotics
Fix Zole (Metronidazole) 250/500mg Targets anaerobic bacteria and protozoa including Hexamita and hole-in-the-head disease in ornamental fish. Available in 60-count bottles. Shop Fix Zole
Fix Doxy (Doxycycline) 100mg A tetracycline-class fish and bird antibiotic effective against columnaris, respiratory infections and Mycoplasma. Available in 30-count and 60-count tablets. Shop Fix Doxy
Fix Zithro (Azithromycin) 250mg A macrolide fish and bird antibiotic for fin rot, columnaris, gill disease and avian respiratory concerns. Available in 12-count and 30-count tablets. Shop Fix Zithro
Fix Cin (Clindamycin) 150mg A lincosamide fish antibiotic commonly used for gram-positive bacterial infections including skin and soft tissue concerns in ornamental fish. Shop Fix Cin
Fix Sulfa (SMZ/TMP) 960mg A sulfonamide combination fish antibiotic offering broad-spectrum coverage against a range of bacterial infections in ornamental fish. Shop Fix Sulfa
Fix Pen (Penicillin) 500mg A penicillin-type fish and bird antibiotic for gram-positive bacterial infections in ornamental fish and non-food pet birds. Shop Fix Pen
Fix Flex (Cephalexin) 250/500mg A first-generation cephalosporin fish and bird antibiotic for fin rot, ulcers and bacterial skin infections in ornamental fish. Shop Fix Flex
Fix Flox (Ciprofloxacin) 500mg A fluoroquinolone fish and bird antibiotic for gram-negative bacterial infections including fin rot, ulcers, columnaris and septicemia in ornamental fish. Shop Fix Flox
Guides and treatment tips Visit the Fish & Bird Antibiotics Blog for practical dosing guides, water-care advice and treatment tips.
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About Fine PetHealth and How We Verify Our Antibiotic Guides
Who is responsible for this page: Fine PetHealth Editorial Team.
Verification snapshot: This guide is written from the current product label for this item and reviewed for accuracy and consistency before publishing.
How we verify product information (our checklist):
1) Label-first accuracy: Dosing, duration, storage, and warnings are taken from the current product label for this item.
2) Ingredient validation: Active ingredient names are cross-checked against reputable references (for example, NIH PubChem) to reduce the risk of labeling mistakes.
3) Consistency checks: We review for internal consistency (the same dosing and storage language across sections) and remove wording that could overpromise results.
4) Updates: We update pages when label directions, packaging, or manufacturer information changes.
What we don’t do: We don’t invent diagnoses, and we don’t create dosing instructions beyond what the product label states for this item’s intended use.
See something that doesn’t match your bottle? Please contact us so we can review and update the page:
Contact Fine PetHealth.
Educational use: Our content is for informational purposes and is not a substitute for diagnosis or treatment from an aquatic or avian veterinarian.
Just what I needed -
Great communication regarding delivery!
Hey Jenny! Thanks for the wonderful feedback. We know how important it is to get exactly what you need for your aquarium quickly, so we always try to keep our communication regarding delivery as clear and helpful as possible. Thanks for choosing us!
J
Jeff Swearingen (Springfield, MO)
Fix Mox 500
Cheapest Price I Could Fine ONLINE Thanks!
Hi Jeff, thank you for the 5-star review! We work hard to offer the best prices online, so we are thrilled you found a great deal on the Fix Mox 500 for your aquarium. We truly appreciate your support!
D
Dolores Bott (Pittsburgh, PA)
Works
It works quite well.
Hey Dolores! Thanks for the great rating and for letting us know the Fix Mox did the job. It is always fantastic to hear when an aquarium is back on track. See you next time!
c
cindy roberts (Marysville, CA)
Review of FinePet first order
My first order was great price, easy to order and fast delivery. I order for Rescue group so every penny (or nickel now) counts
Thank you for the fantastic review, Cindy! It is great to know that our fast shipping and pricing hit the mark for your first order. We have immense respect for rescue groups and are always happy to provide reliable supplies for your aquariums. We truly appreciate your support and look forward to helping you again!
T
Terry Kerley (Beaumont, CA)
Amoxicillan
Shipped quickly.
Have not used it yet.
Hi Terry, thank you for the great review! We always aim for fast shipping, so it is awesome to know your order arrived quickly. We hope the Fix Mox does the job wonderfully for your fish when the time comes.
