Direct from Aqua Soma Labs with extended expiration dates.
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Fix Doxy (Fish Doxy) Doxycycline Tablets - 100 mg
Fix Doxy at a Glance
For
Ornamental aquarium fish and non-food pet birds
Helps with
Fin and tail rot, columnaris, gill disease, septicemia, and avian respiratory infections
Form
Tablets, 100 mg each
Count sizes
30-count and 60-count bottles
Water type
Freshwater and saltwater
Made in
United States, by Aqua Soma Labs
Fix Doxy delivers doxycycline hyclate 100 mg per tablet for ornamental aquarium fish and non-food pet birds, made by Aqua Soma Labs. It is used when bacterial problems appear, such as fin and tail rot, columnaris (often seen as cotton wool disease), bacterial hemorrhagic septicemia, and other internal bacterial infections in freshwater and saltwater aquariums. It is also chosen for racing pigeons and other pet birds during respiratory infections, mycoplasmosis (mycoplasma), or suspected chlamydiosis (also known as parrot fever, psittacosis, or ornithosis).
If you used to buy the discontinued Thomas Labs Fish Doxy, Aqua Doxy, or older Bird Biotic, Fix Doxy is the online replacement. It supplies the same doxycycline strength in bottles of 30 or 60 tablets with fresh expiration dates, and it is a straightforward option when you need doxycycline for birds or a fish doxycycline product to buy online.
Use Fix Doxy when you notice early signs of bacterial stress in your fish or pet birds. Common symptoms differ between species, so check the lists below to identify what to watch for.
Addressing potential bacterial issues early with doxycycline, together with good water quality and advice from an aquatic or avian professional when available, helps your fish and birds maintain a stable, healthy aquarium or aviary.
Order online and ship directly from our U.S. warehouse. Fix Doxy doxycycline 100 mg tablets are available to buy online with same-day dispatch on orders placed before 1:30 p.m. CT, Monday through Friday.
Important Notice: This product is intended for aquarium and ornamental fish and pet birds only. It is not for animals used for food.
Fish Doxy vs Fix Doxy: What Changed?
If you used to buy Fish Doxy, Aqua Doxy, or Bird Biotic from Thomas Labs, here is what stayed the same and what is different with Fix Doxy from Aqua Soma Labs.
Same Doxycycline Fix Doxy delivers the same doxycycline hyclate 100 mg per tablet that was used in the original Fish Doxy and Bird Biotic products.
New Manufacturer Fix Doxy is made by Aqua Soma Labs, replacing Thomas Labs, which discontinued its Fish Doxy and Bird Biotic lines.
Same Tablet Form 100 mg tablets with the same dosing style (1 tablet per 15 gallons), so switching from Fish Doxy to Fix Doxy requires no changes to your routine.
Updated Packaging & Labeling New bottle design and labeling under the Fix brand, with the same doxycycline formula and fresh expiration dates.
Benefits of Fix Doxy for Fish & Birds
Targets Common Bacterial Problems
Helps manage common bacterial problems such as fin and tail rot, columnaris, gill disease, septicemia, internal bacterial infections, and avian respiratory infections caused by certain Gram-positive and Gram-negative bacteria in both freshwater and saltwater aquariums.
Made in the United States
Fix Doxy is manufactured by Aqua Soma Labs and ships from a U.S. warehouse with fresh expiration dates, so you receive a recently made product ready for your tank or aviary.
One Solution for Fish & Birds
Fix Doxy is formulated for both ornamental aquarium fish and non-food pet birds, so one doxycycline product covers tanks and aviaries. Use it for individual treatment or a whole flock as appropriate.
Fixed 100 mg Tablets
Each tablet delivers a fixed 100 mg doxycycline amount. These fish doxycycline tablets make it easier to follow the charts and repeat treatments accurately across different tank volumes or bird sizes.
Flexible Use in Tanks & Feed
Tablets are water-soluble and easy to crush, so you can dissolve them in a hospital or quarantine tank, or mix them with food or drinking water as directed. This helps when you need to treat sensitive fish or birds.
Available in 30-Count and 60-Count Bottles
Choose a 30-count bottle for a single treatment or a 60-count bottle for larger tanks, multiple birds, or repeat treatments, so you always have doxycycline on hand when needed.
Direct Fish Doxy & Bird Biotic Replacement
Fix Doxy replaces the discontinued Fish Doxy (Thomas Labs), Aqua Doxy, and Bird Biotic products. It delivers the same doxycycline hyclate 100 mg per tablet that hobbyists and breeders used before those lines were discontinued.
Usage Guidelines & Instructions
Directions for Use:
Prepare a Separate Treatment Area
For fish, set up a hospital or quarantine tank with clean, dechlorinated water so you can treat without disturbing the main display tank or its biofilter. Any aquarium doxycycline treatment works best in a separate tank, so remove activated carbon, resins and UV sterilizers during dosing, as they can strip doxycycline from the water.
Calculate and Give the Dose
Fish: Check the dosing instructions on your Fix Doxy bottle. Label directions for 100 mg tablets typically call for 1 tablet (100 mg) per 15 gallons (57 L) of water, repeated every 24 hours for several days. Pre-dissolve the tablet in a small cup of tank water, then add it evenly around the treatment tank.
Birds: For companion birds, the amount is based on the bird's weight or the volume of treated drinking water. Crush the tablet and mix with soft food or a measured amount of drinking water only as directed on the packaging or by an avian veterinarian, making sure the bird receives the full intended amount.
Monitor Progress and Water Quality
Watch appetite, breathing, activity level and fin or feather condition every day. If symptoms worsen or no improvement is seen after several days, contact a veterinarian. For fish, perform partial water changes between doses if water quality declines, then re-dose for the new water volume. Continue treatment for the full number of days recommended on the label, usually around 5 to 10 days, unless your vet advises otherwise, and never exceed label directions.
Fix Doxy Amounts by Aquarium Size
Tank volume
100 mg tablets per use
15 gallons (57 L)
1
30 gallons (114 L)
2
45 gallons (170 L)
3
60 gallons (227 L)
4
75 gallons (284 L)
5
These figures follow the label directions of one dissolved tablet per 15 gallons of water. Dose by the water volume of your treatment tank, not by the number of fish, give one dose every 24 hours with a partial water change between doses, and round to the nearest practical tablet. 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 discolored. 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. The label says to discontinue use if no improvement is seen after 5 days, so 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 number of days so the infection does not return. Afterward, run a partial water change and put activated carbon back in to clear any leftover doxycycline.
What You Need for Treatment
A little setup before the first dose saves trouble later.
A separate hospital or quarantine tank, so you are not treating 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 for dissolving each tablet.
Pro Tip: Keep a few extra Fix Doxy tablets on hand so you always have them ready at the first sign of bacterial stress. A quarantine tank with a heater and sponge filter makes treatment faster and protects your main system.
How Fix Doxy Works
Fix Doxy uses doxycycline hyclate 100 mg per tablet to help control certain Gram-positive and Gram-negative bacteria linked with fin and tail rot, mouth rot, columnaris, gill disease, septicemia, and avian respiratory infections. The tablets dissolve readily in aquarium water, and they can also be crushed and mixed with soft food or drinking water, which spreads the dose evenly through a treatment tank or across a flock.
Safety and Tank Notes
When used as directed, Fix Doxy usually causes no problems in ornamental fish and pet birds. As with any doxycycline product, incorrect amounts or prolonged use can increase the risk of side effects.
Fish
Doxycycline based fish treatments may cause temporary stress or hiding behavior, mild water discoloration and reduced appetite during treatment. If fish show severe distress such as rapid gill movement, loss of balance or gasping at the surface, stop treatment and seek aquatic veterinary advice.
Birds
When doxycycline is given in food or drinking water, potential reactions can include decreased appetite, lethargy or changes in droppings if the amount is too high or the bird is sensitive. If your bird appears fluffed up, inactive or stops eating, discontinue use and contact an avian veterinarian.
Invertebrates
Do not use Fix Doxy in tanks that contain shrimp, snails, or other invertebrates, as strong treatments may harm them. Treat fish in a separate hospital tank whenever possible.
Safe Use in Your System
Whenever possible, treat fish in a hospital or quarantine tank, remove activated carbon and UV sterilizers and follow label directions for dose and duration. Do not mix Fix Doxy with other treatments unless advised by a veterinarian.
Important Safety Warning
Fix Doxy is intended for ornamental aquarium fish and non-food pet birds only. It is not for animals raised for food. Store the product in a cool, dry place away from children and pets. Always follow label directions.
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 Doxy used for?
Fix Doxy is a doxycycline hyclate 100 mg antibacterial treatment for ornamental aquarium fish and non-food pet birds. It is used when bacterial problems such as fin and tail rot, columnaris, gill disease, septicemia or respiratory infections in birds are suspected and a veterinarian or experienced aquatic or avian keeper recommends a doxycycline product. It does not treat parasitic, viral or fungal conditions.
What is in Fix Doxy (Fish Doxy)?
Fix Doxy contains doxycycline hyclate 100 mg per tablet. It works against certain Gram-positive and Gram-negative bacteria and is the same doxycycline hyclate that was used in the discontinued Fish Doxy (Thomas Labs), Aqua Doxy, and Bird Biotic products.
What is the difference between Fish Doxy and Fix Doxy?
Fish Doxy was a doxycycline 100 mg product made by Thomas Labs, which has been discontinued. Fix Doxy is a replacement made by Aqua Soma Labs using the same doxycycline hyclate 100 mg and the same tablet-based dosing style. The main difference is the manufacturer and packaging; the doxycycline, strength and general usage directions are the same.
Is Fix Doxy a replacement for Bird Biotic?
Yes. Bird Biotic was a doxycycline hyclate 100 mg product from Thomas Labs intended for pigeons, pet birds, and exotic birds. Fix Doxy contains the same doxycycline at the same strength and can be used for non-food pet birds in the same way. Follow the Fix Doxy label directions for avian dosing.
Is Bird Biotic still available, and is Fix Doxy a true replacement?
Bird Biotic by Thomas Labs has been discontinued and is no longer manufactured. Fix Doxy from Aqua Soma Labs replaces it, supplying the same doxycycline hyclate 100 mg per tablet that pigeon fanciers, bird breeders, and pet bird owners used before. The doxycycline, strength, and dosing approach for non-food pet birds are the same; only the manufacturer and packaging have changed.
Is Fix Doxy the same as Aqua Doxy?
Aqua Doxy was another doxycycline based fish treatment brand. Fix Doxy from Aqua Soma Labs uses the same doxycycline hyclate 100 mg and serves the same purpose. If you previously used Aqua Doxy for your aquarium or aviary, Fix Doxy is a suitable replacement with the same dosing strength.
Can I use Fix Doxy for dogs, cats, or chickens?
No. Fix Doxy is labeled and intended for ornamental aquarium fish and non-food pet birds only. It is not appropriate for dogs, cats, or food-producing animals (including chickens, ducks, turkeys, or other poultry). For dogs and cats, doxycycline should be handled by a veterinarian who can recommend the correct amount and a suitable formulation for the species. Food-producing animals are subject to separate rules and must be treated under veterinary oversight so that withdrawal periods are observed. If your dog, cat, or food-producing animal needs antibacterial treatment, please consult a licensed veterinarian.
Where can I buy doxycycline for fish online?
You can buy Fix Doxy doxycycline 100 mg tablets directly from this page at Fine Pet Health. Orders ship from our U.S. warehouse with same-day dispatch on orders placed before 1:30 p.m. CT, Monday through Friday. Select your preferred bottle size (30-count or 60-count) above and proceed to checkout.
Fix Doxy is only available as 100 mg tablets. If a higher total dose is needed, use multiple 100 mg tablets according to label directions or veterinary guidance. For example, a 500 mg total dose would require five 100 mg tablets. Always measure tank volume or bird body weight carefully before increasing the amount, and never exceed the dosing schedule printed on the Fix Doxy label.
How do I know if my fish or bird might need a treatment like Fix Doxy?
Signs of possible bacterial issues can include frayed or reddened fins, open sores, body patches, labored breathing, nasal discharge, fluffed-up feathers, or a sudden drop in appetite. These signs are not specific to one disease, so a veterinarian or experienced aquatic or avian professional should help confirm whether a doxycycline antibacterial treatment is appropriate.
How long should I treat with Fix Doxy 100 mg?
Most label directions for doxycycline 100 mg tablets call for about 5 to 10 days, with doses given every 24 hours. Do not stop early just because symptoms look better, and never extend the treatment or change the dose beyond what the label or your veterinarian advises.
What size aquarium can one Fix Doxy tablet treat?
Label directions typically call for 1 tablet (100 mg) per 15 gallons (57 L) of water. For a 30-gallon fish tank or hospital tank you would use 2 tablets. Always measure your treatment tank volume carefully and follow the directions on the Fix Doxy label.
Does Fix Doxy work in saltwater aquariums?
Yes. Fix Doxy works against certain Gram-positive and Gram-negative bacteria in both freshwater and saltwater aquariums, so it can be used as a saltwater fish treatment and in freshwater tanks alike. The same dosing directions apply. As always, treat in a hospital or quarantine tank whenever possible to protect your main system's biofilter and invertebrates.
Can I use Fix Doxy in my main display or community tank?
It is usually better to treat in a hospital or quarantine tank. Like other aquarium treatments, Fix Doxy can affect beneficial biofilter bacteria in a community tank. Treating separately helps protect your main system and makes it easier to monitor sick fish.
Will Fix Doxy harm my aquarium's biofilter?
Any strong antibacterial treatment can impact nitrifying bacteria if used in the main tank. Using a separate treatment tank, monitoring ammonia and nitrite, and performing partial water changes as directed helps reduce the risk to your biofilter.
Can Fix Doxy be used for pigeons and other pet birds?
Doxycycline has a long history of use in avian care, including for racing pigeons, parrots, finches, canaries, and other companion birds. Fix Doxy delivers the same doxycycline hyclate 100 mg that was available in Bird Biotic products used by pigeon fanciers and bird breeders. The amount and duration must match the bird's species, size, and condition, so follow the Fix Doxy label directions for non-food pet birds or consult an avian veterinarian before treating. Fix Doxy should not be used for chickens, ducks, or other food-producing birds.
Can I combine Fix Doxy with other fish treatments?
Do not mix Fix Doxy with other treatments unless specifically advised by a veterinarian. Combining treatments can reduce effectiveness, cause harmful interactions, or increase stress on fish. If a second treatment is needed, finish the doxycycline treatment first, perform a water change with activated carbon, and then begin the next one.
What should I do if my fish or bird is not improving on Fix Doxy?
Stop treatment and contact a veterinarian. Lack of improvement can mean the problem is not bacterial, the bacteria do not respond to doxycycline, or the dose or treatment duration is not appropriate. Continuing an ineffective treatment can delay proper care.
How should I store Fix Doxy tablets?
Store Fix Doxy in a cool, dry place away from direct sunlight and moisture, with the bottle tightly closed. Keep out of reach of children and pets. Check the expiration date on the packaging and do not use tablets past that date.
How should I dispose of water or filter media that contained Fix Doxy?
For disposal, follow your local guidance for safe household disposal.
More Fish & Bird Treatments
Fix Mox (Amoxicillin) 250/500mg A treatment for fin rot, dropsy, ulcers and other bacterial infections in ornamental fish. Available in 30-count and 100-count capsules. Shop Fix Mox
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 Zithro (Azithromycin) 250mg A treatment 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 treatment for Gram-positive bacterial infections, including skin and soft tissue concerns in ornamental fish. Shop Fix Cin
Fix Sulfa (SMZ/TMP) 960mg A treatment for a range of bacterial infections in ornamental fish. Shop Fix Sulfa
Fix Pen (Penicillin) 500mg A treatment for Gram-positive bacterial infections in ornamental fish and non-food pet birds. Shop Fix Pen
Fix Flex (Cephalexin) 250/500mg A treatment for fin rot, ulcers and bacterial skin infections in ornamental fish. Shop Fix Flex
Fix Flox (Ciprofloxacin) 500mg A treatment 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 Treatments Blog for practical care guides, water-care advice and treatment tips.
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Hi Moria, thank you for the 5-star review! We are very glad to hear that you experienced good service and consider the Fix Doxy an excellent product. We hope it works perfectly for your aquarium or flock, and we truly appreciate your support!
R
Rosy (Minneapolis, MN)
Appreciation
Thank you for making these products available!
Hi Mindi, thank you for the fantastic review and your continued trust in us! It is awesome to hear that our products are consistently hitting the mark for your birds. We always aim to provide great prices and efficient shipping, so it's wonderful to know it shows. See you next time!
J
Julie Taylor (Punta Gorda, FL)
Fish doxy
This product was very effective, will order again..
Hi Julie, thank you for the fantastic review! It is great to know that the Fix Doxy did the job perfectly and helped out. Thanks for choosing us, and we can't wait to see you again for your next restock!
R
Ray (Stafford, NY)
Product as advertised
Fast shipment and received exactly what I ordered. Good business. Recommended.
Hi Ray! It brings us so much joy to read your wonderful words and see your recommendation. We are thrilled that the quick shipping and the accuracy of your Fix Doxy order hit the mark for you. Doing good business with great customers like you is our top priority, and we cannot wait to welcome you back to our store soon!
G
Gregory Gibbert (Grand Junction, CO)
Fix Doxy (Doxycycline) 100mg 30/60ct Fish Antibiotic
Hi Gregory! A massive thank you for the wonderful 5-star rating on your recent purchase of Fix Doxy. We are absolutely thrilled to know that you are completely satisfied with the item. We value your business immensely and cannot wait to welcome you back the next time you need to stock up!
