{"product_id":"fix-pen-500mg-otc-fish-bird-penicillin","title":"Fix Pen (Fish Pen) Penicillin 500mg 30\/60ct Fish \u0026 Bird Antibiotic","description":"\u003cdiv class=\"fph-product-copy\"\u003e\n\u003csection id=\"overview\" class=\"fph-section\"\u003e\n\u003ch2\u003eFix Pen (Fish Pen Forte) Penicillin Tablets - 500 mg\u003c\/h2\u003e\n\u003cnav class=\"fph-toc\" aria-label=\"On this page\"\u003e\u003cspan class=\"fph-toc-label\"\u003eOn this page:\u003c\/span\u003e \u003ca href=\"#overview\"\u003eOverview\u003c\/a\u003e \u003ca href=\"#fish-pen-vs-fix-pen\"\u003eFish Pen vs Fix Pen\u003c\/a\u003e \u003ca href=\"#benefits\"\u003eBenefits\u003c\/a\u003e \u003ca href=\"#dosage\"\u003eDosage\u003c\/a\u003e \u003ca href=\"#mechanism\"\u003eHow It Works\u003c\/a\u003e \u003ca href=\"#side-effects\"\u003eSide Effects\u003c\/a\u003e \u003ca href=\"#shipping\"\u003eShipping\u003c\/a\u003e \u003ca href=\"#faq\"\u003eFAQ\u003c\/a\u003e\u003c\/nav\u003e\n\u003cp\u003e\u003cstrong\u003eFix Pen (Fish Pen) Penicillin 500mg\u003c\/strong\u003e is a pharmaceutical-grade, over-the-counter (OTC) penicillin fish and bird antibiotic for ornamental aquarium fish and non-food pet birds. Manufactured by \u003cstrong\u003eAqua Soma Labs\u003c\/strong\u003e in the United States, Fix Pen delivers \u003cstrong\u003e500 mg Penicillin V Potassium (Penicillin VK)\u003c\/strong\u003e per tablet and is available in bottles of \u003cstrong\u003e30 or 60 tablets\u003c\/strong\u003e with fresh expiration dates.\u003c\/p\u003e\n\u003cp\u003eOften called Fish Pen, Fish Pen Forte, Aqua Pen or FISHBIOTIC Penicillin in the hobby community, Fix Pen is frequently sought as a reliable online alternative to discontinued Thomas Labs Fish Pen and Fish Pen Forte products. Hobbyists commonly discuss penicillin tablets for fish in connection with issues described as fin rot, tail rot, infected wounds, secondary skin infections, pop-eye (bulging eyes), columnaris-type lesions (often presenting as cotton-wool disease) or flexibacter-type problems when a bacterial component is suspected.\u003c\/p\u003e\n\u003cp\u003ePenicillin V is a beta-lactam antibiotic that works by interfering with bacterial cell wall formation, which can help stop susceptible gram-positive bacteria from multiplying. When people search for \"fish pen penicillin,\" \"penicillin for fish tank,\" \"fish penicillin 500mg\" or \"bird penicillin,\" they are typically looking for a product like Fix Pen that targets gram-positive and some gram-negative bacterial infections in aquarium settings.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFix Pen\u003c\/strong\u003e from Aqua Soma Labs provides \u003cstrong\u003e500 mg\u003c\/strong\u003e per tablet and comes in bottles of \u003cstrong\u003e30 or 60 tablets\u003c\/strong\u003e for flexible planning whether you maintain a single hospital tank, multiple community aquariums, or need a convenient option for pet birds under veterinary guidance. Buy Fix Pen online with fresh expiration dates and reliable U.S. shipping.\u003c\/p\u003e\n\u003cp\u003eUse Fix Pen when you notice early signs that may be consistent with a bacterial problem such as reduced appetite, lethargy, reddening, sores, ulcers, frayed or worsening fin damage, pop-eye or cloudy eyes in fish. For birds, use penicillin only with veterinary direction and monitoring, especially for respiratory or soft tissue infections where your vet suspects a susceptible organism. Addressing potential bacterial issues early, together with good water quality and appropriate husbandry, helps your fish and birds maintain a stable, healthy environment.\u003c\/p\u003e\n\u003cp\u003eGood husbandry still matters: stable parameters, clean water, and appropriate nutrition are the foundation of a healthy aquarium or aviary. Penicillin does not help with viral problems, and using antibiotics when they are not needed can reduce future effectiveness.\u003c\/p\u003e\n\u003cp class=\"fph-tip\"\u003e\u003cstrong\u003eOrder online\u003c\/strong\u003e and enjoy same-day dispatch on orders placed before 1:30 p.m. CT, Monday through Friday. Fix Pen ships directly from our U.S. warehouse via USPS or UPS.\u003c\/p\u003e\n\u003cp class=\"fph-alert\"\u003e\u003cstrong\u003eImportant Notice:\u003c\/strong\u003e This product is \u003cstrong\u003eintended for aquarium and ornamental fish and pet birds only\u003c\/strong\u003e. It is \u003cstrong\u003enot for human consumption\u003c\/strong\u003e or for \u003cstrong\u003eanimals used for food\u003c\/strong\u003e. We \u003cstrong\u003edo not sell or recommend this product for human use\u003c\/strong\u003e.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003csection id=\"fish-pen-vs-fix-pen\" class=\"fph-section\"\u003e\n\u003ch2\u003eFish Pen Forte vs Fix Pen: What Changed?\u003c\/h2\u003e\n\u003cp\u003eIf you previously purchased Thomas Labs Fish Pen, Fish Pen Forte, Aqua Pen or FISHBIOTIC Penicillin, here is what has changed and what remains the same:\u003c\/p\u003e\n\u003cdiv class=\"fph-info-grid\"\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eSame Active Ingredient\u003c\/strong\u003e Fix Pen contains the same \u003cstrong\u003e500 mg Penicillin V Potassium (Penicillin VK)\u003c\/strong\u003e per tablet that you relied on with Fish Pen and Fish Pen Forte. The pharmaceutical-grade formulation targets the same bacteria.\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eNew Manufacturer\u003c\/strong\u003e Fix Pen is made by \u003cstrong\u003eAqua Soma Labs\u003c\/strong\u003e, replacing the discontinued Thomas Labs line. Aqua Soma Labs manufactures in the United States under strict quality-control standards.\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eSame Tablet Form\u003c\/strong\u003e Fix Pen uses the same \u003cstrong\u003etablet\u003c\/strong\u003e format as the original Fish Pen, making it easy to dissolve in aquarium water or crush for precise dosing in a hospital tank.\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eAvailable in 30-Count and 60-Count Bottles\u003c\/strong\u003e Choose the size that fits your setup: a 30-count bottle for a single hospital tank or occasional use, or a 60-count bottle for larger collections, multi-tank operations or aviary needs.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003csection id=\"benefits\" class=\"fph-section\"\u003e\n\u003ch2\u003eBenefits of Fix Pen for Fish \u0026amp; Birds\u003c\/h2\u003e\n\u003cul class=\"fph-card-list\"\u003e\n\u003cli\u003e\n\u003ch3\u003eTargeted Gram-Positive Bacterial Coverage\u003c\/h3\u003e\n\u003cp\u003eA classic penicillin option commonly chosen when a gram-positive bacterial component is suspected in ornamental fish, especially when signs look consistent with issues hobbyists describe as fin and tail rot, mouth rot, sores, pop-eye or cloudy eyes.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eNo Prescription Required\u003c\/h3\u003e\n\u003cp\u003eFix Pen is available over the counter for aquarium and avian use, so you can start treatment promptly without waiting for a prescription. For birds, professional veterinary guidance is still strongly recommended to determine the correct dose and duration.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eConsistent 500 mg Tablets\u003c\/h3\u003e\n\u003cp\u003eEach tablet delivers a reliable \u003cstrong\u003e500 mg dose\u003c\/strong\u003e of Penicillin V Potassium, making it easier to scale treatment from a single betta or quarantine tank up to larger community aquariums without complicated calculations.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eCommon Aquarium Use Cases\u003c\/h3\u003e\n\u003cp\u003eOften chosen when the label-aligned goal is to target gram-positive and some gram-negative bacteria in ornamental fish. In aquarium care discussions, penicillin is mentioned for problems described as flexibacter-type issues, infected wounds and worsening fin damage when a bacterial component is suspected.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eFreshwater and Saltwater Compatible\u003c\/h3\u003e\n\u003cp\u003eDesigned for ornamental aquarium use in both freshwater and saltwater setups when used as directed. A separate hospital tank is still recommended when possible to protect the main display system.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eQuarantine-Friendly and Biofilter Aware\u003c\/h3\u003e\n\u003cp\u003ePenicillin may affect beneficial bacteria and can be risky for invertebrates like shrimp and snails. A separate treatment tank helps protect the main display system and makes water-quality monitoring easier during the treatment course.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eIdeal for Hospital Tanks and Quarantine\u003c\/h3\u003e\n\u003cp\u003eUsing Fix Pen in a separate hospital tank helps protect the main aquarium's biofilter and reduces unnecessary exposure of healthy tank mates while you focus treatment where it is needed most.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003csection id=\"dosage\" class=\"fph-section\"\u003e\n\u003ch2\u003eDosage Guidelines \u0026amp; Instructions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eQuick dosing summary for fish:\u003c\/strong\u003e Use \u003cstrong\u003e1 tablet per 20 gallons (76 L)\u003c\/strong\u003e, repeat every 24 hours, and do a partial water change between doses. Continue for \u003cstrong\u003e5 to 10 days\u003c\/strong\u003e, and discontinue if no improvement is noted after 5 days.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDirections for Use:\u003c\/strong\u003e\u003c\/p\u003e\n\u003col class=\"fph-step-list\"\u003e\n\u003cli\u003e\n\u003ch3\u003eSet Up a Separate Treatment Area\u003c\/h3\u003e\n\u003cp\u003eWhen possible, treat fish in a hospital or quarantine tank. This helps limit exposure for healthy tank mates and makes it easier to monitor results and water quality. Remove activated carbon and turn off UV sterilizers during treatment, as they can remove the medication from the water.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eDose for Fish Aquariums\u003c\/h3\u003e\n\u003cp\u003eDissolve \u003cstrong\u003eone (1) 500 mg tablet\u003c\/strong\u003e in a small cup of aquarium water first, then add the dissolved dose for every \u003cstrong\u003e20 gallons (76 L)\u003c\/strong\u003e of water to be treated. Repeat every \u003cstrong\u003e24 hours\u003c\/strong\u003e, and make a partial water change between treatments.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eDuration and When to Stop\u003c\/h3\u003e\n\u003cp\u003eContinue treatment for \u003cstrong\u003e5 to 10 days\u003c\/strong\u003e. If no improvement is noted after 5 days, discontinue use and consider consulting an aquatic professional for next-step options. Complete the full recommended course even if fish appear better, as stopping early can allow symptoms to return.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eMaintain Water Quality During Treatment\u003c\/h3\u003e\n\u003cp\u003eKeep strong aeration and closely monitor water parameters (especially ammonia and nitrite). Because penicillin may affect beneficial bacteria and can be risky for invertebrates like shrimp and snails, a separate treatment tank and close observation are strongly recommended.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003ePet Birds (Under Veterinary Guidance Only)\u003c\/h3\u003e\n\u003cp\u003eFor non-food pet birds, use penicillin only under avian veterinary guidance for dosing, frequency and duration. Your vet can advise you on the correct mg-per-kg dose and decide whether to treat a single bird or an entire flock.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp class=\"fph-tip\"\u003e\u003cstrong\u003ePro Tip:\u003c\/strong\u003e Dose based on the actual treated water volume (not the aquarium's advertised size), since gravel, decorations and equipment reduce usable volume. Consistent daily observation and stable water quality often make the biggest difference during suspected bacterial outbreaks.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003csection id=\"mechanism\" class=\"fph-section\"\u003e\n\u003ch2\u003eHow This Medication Works\u003c\/h2\u003e\n\u003cul class=\"fph-card-list\"\u003e\n\u003cli\u003e\n\u003ch3\u003eActive ingredient: Penicillin V Potassium (Penicillin VK) 500 mg\u003c\/h3\u003e\n\u003cp\u003ePenicillin V is a beta-lactam antibiotic that works by targeting bacterial cell wall formation. It binds to penicillin-binding proteins (PBPs) involved in peptidoglycan cross-linking, which can help control susceptible gram-positive bacteria and some gram-negative bacteria when used as directed in ornamental fish care.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eInactive ingredients\u003c\/h3\u003e\n\u003cp\u003eTablet excipients that help keep the active ingredient stable on the shelf and allow the tablet to disperse and dissolve properly when added to aquarium water or treatment setups.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003cdiv id=\"side-effects\" class=\"fph-panel\"\u003e\n\u003ch2\u003eSide Effects \u0026amp; Safety Tips\u003c\/h2\u003e\n\u003cp\u003eWhen used as directed, Fix Pen is typically well tolerated in ornamental fish. As with any antibiotic, unnecessary use, incorrect dosing or combining treatments can increase stress and reduce future effectiveness.\u003c\/p\u003e\n\u003cul class=\"fph-card-list\"\u003e\n\u003cli\u003e\n\u003ch3\u003eFish\u003c\/h3\u003e\n\u003cp\u003eSome fish may show temporary stress, reduced appetite or hiding behavior during treatment. If you notice severe distress such as rapid gill movement, loss of balance, gasping at the surface or fish lying on the bottom, stop treatment, improve aeration, perform a partial water change and seek aquatic veterinary or professional guidance.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eBirds\u003c\/h3\u003e\n\u003cp\u003eFor non-food pet birds, use penicillin only under avian veterinary guidance. If your bird becomes unusually lethargic, stops eating or appears unwell, discontinue use and contact your avian veterinarian immediately.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eInvertebrates\u003c\/h3\u003e\n\u003cp\u003eDo not use Fix Pen in display tanks that contain shrimp, snails or other invertebrates, as penicillin may harm them or disrupt the tank ecosystem. Whenever possible, move affected fish to a separate hospital tank.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eSafe use in your system\u003c\/h3\u003e\n\u003cp\u003eTreat fish in a hospital or quarantine tank whenever you can, remove activated carbon and turn off UV sterilizers during treatment, and monitor ammonia, nitrite and temperature closely. Do not mix Fix Pen with other antibiotics unless advised by a veterinarian.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003eImportant safety warning\u003c\/h3\u003e\n\u003cp\u003eFix Pen is intended for \u003cstrong\u003eornamental aquarium fish and non-food pet birds only\u003c\/strong\u003e. \u003cspan class=\"fph-inline-warning\"\u003eIt is not for human use\u003c\/span\u003e and not for animals raised for food. Using fish or bird antibiotics in people instead of prescribed medicine can lead to treatment failure, serious side effects and antibiotic resistance. Store tablets in a cool, dry place away from direct sunlight and keep out of reach of children and pets. Always follow the directions on the label.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003chr\u003e\n\u003csection id=\"shipping\" class=\"fph-section\"\u003e\n\u003ch2\u003eShipping \u0026amp; Returns\u003c\/h2\u003e\n\u003cdiv class=\"fph-info-grid\"\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eShipping Policy:\u003c\/strong\u003e Orders ship from our U.S. warehouse within 1 business day via USPS or UPS, with same-day dispatch on orders placed before 1:30 p.m. CT (Monday through Friday). For full shipping details, please see our \u003ca href=\"https:\/\/finepethealth.com\/policies\/shipping-policy\"\u003eshipping policy\u003c\/a\u003e.\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eRefund Policy:\u003c\/strong\u003e 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 \u003ca href=\"https:\/\/finepethealth.com\/policies\/refund-policy\"\u003erefund policy\u003c\/a\u003e carefully.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003csection id=\"faq\" class=\"fph-section\"\u003e\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"fph-faq-list\"\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eWhat is Fix Pen used for?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eFix Pen (Penicillin 500 mg) is a penicillin-based fish antibiotic used by hobbyists to help manage suspected bacterial problems in ornamental aquarium fish, particularly gram-positive infections such as fin rot, tail rot, infected wounds, pop-eye and columnaris-type lesions. For non-food pet birds, penicillin should be used only under avian veterinary guidance for dosing and treatment decisions.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eWhat is the difference between Fish Pen Forte and Fix Pen?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eFish Pen and Fish Pen Forte were brand names used by Thomas Labs for their penicillin fish antibiotic tablets. After Thomas Labs discontinued these products, Aqua Soma Labs introduced Fix Pen as a direct replacement. Fix Pen contains the same 500 mg Penicillin V Potassium per tablet and is intended for the same ornamental fish and pet bird applications.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eIs Fix Pen a replacement for FISHBIOTIC Penicillin or Aqua Pen?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eYes. If you previously used FISHBIOTIC Penicillin, Aqua Pen or any other 500 mg penicillin fish antibiotic tablet, Fix Pen from Aqua Soma Labs is a direct replacement with the same active ingredient (Penicillin V Potassium 500 mg per tablet) and is available in 30-count and 60-count bottles.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eDo I need a veterinary prescription to buy Fix Pen?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eNo. Fix Pen is sold over the counter as a fish and bird antibiotic, and no veterinary prescription is required to purchase it. However, for pet birds, professional veterinary guidance is strongly recommended to determine the correct mg-per-kg dose and treatment duration.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eWhere can I buy penicillin fish antibiotic tablets online?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eYou can buy Fix Pen (Penicillin VK 500 mg) directly from 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, via USPS or UPS.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eIs Fix Pen a human Pen VK alternative?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eNo. \u003cspan class=\"fph-inline-warning\"\u003eFix Pen is not a human Pen VK alternative.\u003c\/span\u003e While it contains the active ingredient Penicillin V Potassium, this product is manufactured, packaged and labeled strictly as an over-the-counter penicillin for ornamental aquarium fish and non-food pet birds only. It must never be taken by humans, prescribed to yourself or given to animals raised for food.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eWhat is the active ingredient in each Fix Pen tablet?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eEach Fix Pen tablet contains \u003cstrong\u003e500 mg Penicillin V Potassium (Penicillin VK)\u003c\/strong\u003e. Penicillin V is a beta-lactam antibiotic that works by interfering with bacterial cell wall formation, helping control susceptible gram-positive bacteria when used as directed.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eWhat is the Fix Pen dosage for fish?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eFollow the label directions: add \u003cstrong\u003eone (1) 500 mg tablet per 20 gallons (76 L)\u003c\/strong\u003e of water to be treated, repeat every 24 hours and make a partial water change between doses. Continue for \u003cstrong\u003e5 to 10 days\u003c\/strong\u003e and discontinue use if no improvement is noted after 5 days.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eHow long should I treat with Fix Pen?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eLabel directions recommend treatment for at least 5 days but no more than 10 days. If there is no improvement after 5 days, discontinue treatment and reassess husbandry and next-step options with an aquatic professional.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eShould I treat in the main tank or a hospital tank?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eA separate hospital or quarantine tank is strongly recommended. Antibiotics may impact beneficial bacteria and can be risky for shrimp, snails, corals and other invertebrates, so dosing a display tank or reef setup is generally not recommended. A small, dedicated hospital tank with a heater, air stone and no substrate makes dosing and water changes easier.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eDo I need to remove activated carbon or turn off UV during treatment?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eYes. Activated carbon and some chemical filtration media can remove medications from the water. Remove them during treatment and reinstall after the course is finished. Many keepers also temporarily turn off UV sterilizers during dosing to keep medication levels consistent.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eWill Fix Pen harm beneficial bacteria in the aquarium?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eIt can. Any antibiotic, including penicillin, may affect beneficial filter bacteria if used in the main tank. Using a hospital tank, monitoring ammonia and nitrite and performing partial water changes helps protect the biofilter while treatment is underway.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eCan Fix Pen be used in saltwater aquariums?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eYes. Fix Pen can be used in both freshwater and saltwater hospital tanks. Dissolve the tablet following the standard dosage (one 500 mg tablet per 20 gallons) and maintain stable salinity, temperature and water quality parameters throughout the treatment course.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eIs Fix Pen safe for betta fish and small aquariums?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eYes. Fix Pen can be used in small hospital tanks for bettas and other individual fish. Because bettas are often kept in tanks under 20 gallons, you may need to split a tablet to achieve the correct dose (one 500 mg tablet per 20 gallons). Dissolve the portion in a small cup of tank water before adding it to the hospital tank.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eCan I use Fix Pen in a planted tank or with shrimp and snails?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eIt is generally considered compatible with most planted tanks, but penicillin may harm shrimp, snails and other invertebrates. When possible, move affected fish to a separate hospital tank to reduce plant and biofilter exposure during treatment and protect invertebrates.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eCan Fix Pen treat fungal, viral or parasitic infections?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eNo. Fix Pen is a penicillin antibiotic that targets certain bacterial infections only. It is not effective against fungi, viruses or parasites such as ich, flukes or worms. For fungal, parasitic or viral problems, work with an aquatic or avian veterinarian to choose an appropriate treatment.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eCan I combine Fix Pen with other fish medications?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eCombining antibiotics or mixing Fix Pen with antifungal or antiparasitic medications is generally not recommended unless specifically advised by an aquatic veterinarian. Using multiple medications at once can stress fish, cause unpredictable interactions and make it harder to identify which treatment is working.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eCan I use Fix Pen for dogs, cats or chickens?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eFix Pen is labeled and intended for ornamental aquarium fish and non-food pet birds only. It is not formulated, tested or approved for use in dogs, cats, chickens or any other mammals or food-producing animals. If your pet needs penicillin, consult a licensed veterinarian who can prescribe the correct product and dose for that species.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eDoes Fix Pen discolor the water?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eFix Pen tablets typically dissolve without staining or dyeing the water. If you notice cloudiness during treatment, focus on aeration and water-quality monitoring rather than assuming the cloudiness is caused by the medication itself.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"fph-faq-item\"\u003e\n\u003csummary\u003eHow should I store and dispose of Fix Pen tablets?\u003c\/summary\u003e\n\u003cdiv class=\"fph-faq-answer\"\u003e\n\u003cp\u003eStore tablets in their original container in a cool, dry place away from heat, moisture, children and pets. Check the expiration date on the packaging before use. For disposal, a local medicine take-back program is the best option. If a take-back option is not available, follow FDA\/EPA guidance for household medication disposal and avoid flushing unless the label specifically instructs it.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003csection class=\"fph-section\"\u003e\n\u003ch2\u003eMore Fish \u0026amp; Bird Antibiotics\u003c\/h2\u003e\n\u003cdiv class=\"fph-info-grid\"\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Mox (Amoxicillin) 250\/500mg\u003c\/strong\u003e A broad-spectrum penicillin-type fish antibiotic for fin rot, dropsy, ulcers and other bacterial infections. Available in 30-count and 100-count capsules. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-mox-amoxicillin-capsules-fish-antibiotics\"\u003eShop Fix Mox\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Zole (Metronidazole) 250\/500mg\u003c\/strong\u003e Targets anaerobic bacteria and protozoa including Hexamita and hole-in-the-head disease in ornamental fish. Available in 60-count bottles. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-zole-250-metronidazole-250mg-60-doses\"\u003eShop Fix Zole\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Doxy (Doxycycline) 100mg\u003c\/strong\u003e A tetracycline-class fish and bird antibiotic effective against columnaris, respiratory infections and Mycoplasma. Available in 30-count and 60-count tablets. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-doxy-doxycycline-100mg-30-tablets\"\u003eShop Fix Doxy\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Zithro (Azithromycin) 250mg\u003c\/strong\u003e A macrolide fish and bird antibiotic for fin rot, columnaris, gill disease and avian respiratory concerns. Available in 12-count and 30-count tablets. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-zithro-azithromycin-250\"\u003eShop Fix Zithro\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Cin (Clindamycin) 150mg\u003c\/strong\u003e A lincosamide fish antibiotic commonly used for gram-positive bacterial infections including skin and soft tissue concerns in ornamental fish. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-cin-clindamycin-150-fish-antibiotic\"\u003eShop Fix Cin\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Sulfa (SMZ\/TMP) 960mg\u003c\/strong\u003e A sulfonamide combination fish antibiotic offering broad-spectrum coverage against a range of bacterial infections in ornamental fish. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-sulfa-960-mg-otc-fish-antibiotic\"\u003eShop Fix Sulfa\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Flex (Cephalexin) 250\/500mg\u003c\/strong\u003e A first-generation cephalosporin fish and bird antibiotic for fin rot, ulcers and bacterial skin infections in ornamental fish. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-flex-cephalexin-fish-bird-antibiotic\"\u003eShop Fix Flex\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eFix Flox (Ciprofloxacin) 500mg\u003c\/strong\u003e A fluoroquinolone fish and bird antibiotic for gram-negative bacterial infections including fin rot, ulcers, columnaris and septicemia in ornamental fish. \u003ca href=\"https:\/\/finepethealth.com\/products\/fix-flox-ciprofloxacin-500\"\u003eShop Fix Flox\u003c\/a\u003e\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eBrowse all treatments\u003c\/strong\u003e Explore our complete \u003ca rel=\"noopener\" href=\"https:\/\/finepethealth.com\/collections\/fish-and-bird-antibiotics\"\u003e\u003cstrong\u003eFish \u0026amp; Bird Antibiotics Collection\u003c\/strong\u003e\u003c\/a\u003e for more Fix line products and related treatments.\u003c\/p\u003e\n\u003cp class=\"fph-info-card\"\u003e\u003cstrong\u003eGuides and treatment tips\u003c\/strong\u003e Visit the \u003ca rel=\"noopener\" href=\"https:\/\/finepethealth.com\/blogs\/fish-and-bird-antibiotics\"\u003e\u003cstrong\u003eFish \u0026amp; Bird Antibiotics Blog\u003c\/strong\u003e\u003c\/a\u003e for practical dosing guides, water-care advice and treatment tips.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003chr\u003e\n\u003c\/div\u003e","brand":"Aqua Soma Labs","offers":[{"title":"500-mg (30 Count)","offer_id":51178809032989,"sku":"641666","price":59.99,"currency_code":"USD","in_stock":true},{"title":"500-mg (60 Count)","offer_id":51178809065757,"sku":"811298","price":89.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0987\/3863\/5037\/files\/fix-pen-penicillin-500mg-30-count-fish-antibiotic..webp?v=1776421581","url":"https:\/\/finpetmeds.com\/products\/fix-pen-500mg-otc-fish-bird-penicillin","provider":"FINPETMEDS","version":"1.0","type":"link"}