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10 Best Goldfish Antibiotics for Different Diseases in 2022 – Reviews & Top Picks

Lindsey Stanton Profile Picture

By Lindsey Stanton

 

Sick goldfish lying

Keeping goldfish is usually a pretty laid-back, enjoyable hobby. However, goldfish can get sick just like any other animal and it can be confusing trying to sort through all the products on the market to find the right antibiotic. In fact, it can be confusing to even identify what products actually contain an antibiotic.

We’ve put together these reviews of the 10 best goldfish antibiotics to help you have a better idea of what products are available, what they treat, and what products contain antibiotics. Having this knowledge will help you be a better, more well-prepared fish keeper. Keep in mind that different antibiotics treat different diseases, so the number 1 product on this list isn’t necessarily the best option for treating all diseases.

A Quick Comparison of Our Favorites in 2022

Rating Image Product Details
Winner
Fish Aid Antibiotics Cephalexin Capsules Fish Aid Antibiotics Cephalexin Capsules
  • Cost-effective for small and large tanks
  • Two dose sizes available
  • Doesn’t tint the water
  • Second place
    Fish Aid Antibiotics Amoxicillin Capsules Fish Aid Antibiotics Amoxicillin Capsules
  • Two dose sizes available
  • Three bottle sizes available
  • Cost-effective
  • Third place
    Seachem MetroPlex Seachem MetroPlex
  • Effective against gram-negative and gram-positive bacteria
  • Can treat bacterial and protozoal infections
  • Doesn’t tint water
  • Fish Aid Antibiotics Ciprofloxacin Tablets Fish Aid Antibiotics Ciprofloxacin Tablets
  • Two dose sizes available
  • Doesn’t tint the water
  • May see improvements in as little as 5 days
  • Seachem KanaPlex Seachem KanaPlex
  • Powerful antibiotic
  • Can treat fungal and bacterial infections
  • Doesn’t tint water
  • The 10 Best Goldfish Antibiotics for Different Diseases

    1. Fish Aid Antibiotics Cephalexin Capsules

    Fish Aid Antibiotics Cephalexin

    Check Price on Chewy
    Active Ingredients: Cephalexin
    Diseases Treated: Non-specific infections
    Number of Doses Required: 5–10
    Invertebrate Safe: Yes

    Fish Aid Antibiotics Cephalexin Capsules are available in 250 mg and 500 mg dosages and can be purchased in bottles of 30 capsules or 100 capsules. This medication is very cost-effective for tanks of all sizes and is a broad-spectrum antibiotic used to treat non-specific infections that are caused by gram-positive or most gram-negative bacteria. This is a good option if you are unsure of the infection your fish has or if another antibiotic has not shown improvement. This medication is administered by dissolving the contents of the capsules into the tank water. The recommended dosage is 250 mg for every 10 gallons of water. It’s used for 5–10 days and the manufacturer recommends discontinuing use if you don’t see improvements after 5 days.

    Pros
    • Treats gram-positive and gram-negative bacteria
    • Cost-effective for small and large tanks
    • Two dose sizes available
    • Two bottle sizes available
    • Doesn’t tint the water
    • May see improvements in as little as 5 days
    Cons
    • Partial water changes required between doses
    • May be difficult to know when to use

    2. Fish Aid Antibiotics Amoxicillin Capsules

    Fish Aid Antibiotics Amoxicillin

    Active Ingredients: Amoxicillin
    Diseases Treated: Dropsy, fin rot, red pest
    Number of Doses Required: 5–10
    Invertebrate Safe: Yes

    Fish Aid Antibiotics Amoxicillin Capsules are available in 250 mg and 500 mg dosages in bottles of 30 capsules, 60 capsules, and 100 capsules. The recommended dosage of this medication is 250 mg for every 10 gallons and you should open the capsule and add it to your tank water. This medication leaves a yellow tint in the water and partial water changes should be performed between doses. Amoxicillin treats all gram-positive and some gram-negative bacteria, including pseudomonas and aeromonas. This medication can be used to treat dropsy, red pest disease, and fin rot, as well as many other conditions. It’s recommended to use the appropriate dose for a minimum of 5 days but no longer than 10 days. If improvements aren’t seen after 5 days, the manufacturer recommends discontinuing the treatment.

    Pros
    • Treats gram-negative and gram-positive bacteria
    • Two dose sizes available
    • Three bottle sizes available
    • May see improvements in as little as 5 days
    • Cost-effective for small and large tanks
    Cons
    • May tint water yellow
    • Partial water changes required between doses

    3. Seachem MetroPlex

    Seachem MetroPlex Metronidazole Parasite

    Active Ingredients: Metronidazole
    Diseases Treated: Hexamita, ich
    Number of Doses Required: 2–10
    Invertebrate Safe: Usage specific

    Seachem Metroplex is a great antibiotic that the manufacturer states invertebrates may be sensitive to when added to the water. It’s a powder available in one vial size that includes a small scoop for measurements. The dosing is 1–2 scoops for every 10 gallons, but this can also be added to food for fish that are still eating. This medication is extremely bitter, so many fish may refuse to eat it if mixed into medicated food. If dosed in food, invertebrates do not have to be removed from the tank. This medication can be dosed every 48 hours for up to 3 weeks and a vial can treat a 10- or 20-gallon tank for the full dosing schedule. It’s effective against gram-negative and gram-positive bacteria, as well as protozoa like ich.

    Pros
    • Effective against gram-negative and gram-positive bacteria
    • Can treat bacterial and protozoal infections
    • Can be added to tank water or used in medicated food
    • Safe for invertebrates when added to medicated food
    • Can see improvement within 2 doses but can be used up to 3 weeks
    • Doesn’t tint water
    Cons
    • Only one size available
    • Not cost-effective for large tanks
    • Should not be added to water if invertebrates present
    • Extremely bitter taste

    4. Fish Aid Antibiotics Ciprofloxacin Tablets

    Fish Aid Antibiotics Ciprofloxacin

    Active Ingredients: Ciprofloxacin
    Diseases Treated: Fin rot, black patch necrosis, furunculosis
    Number of Doses Required: 5-7
    Invertebrate Safe: Yes

    Fish Aid Antibiotics Ciprofloxacin Tablets are available in 250mg and 500mg tablets and comes in a bottle of 30 tablets. This antibiotic is used by dissolving the tablet in water before adding to the tank and then adding the antibiotic water to a hospital tank once the tablet is fully dissolved. It’s not recommended to add this medication to your regular tank. Dissolve 250 mg for every 1–2 gallons of tank water and use as a bath for your sick fish for 1 hour, then perform a full water change. This medication is used for 5–7 days. It does not tint the water and treats all gram-positive and most gram-negative bacteria, including aeromonas, furunculosis, and columnaris infections like fin rot.

    Pros
    • Treats gram-negative and gram-positive bacteria
    • Two dose sizes available
    • Doesn’t tint the water
    • May see improvements in as little as 5 days
    • Cost-effective when used properly
    Cons
    • Should only be used in a hospital tank as a bath
    • Full water change required between doses
    • One bottle size available

    If you suspect your fish is sick and want to ensure you provide the right treatment, we recommend that you check out our best-selling and comprehensive book The Truth About Goldfish on Amazon today.

    The Truth About Goldfish New Edition

    It has entire chapters dedicated to in-depth diagnoses, treatment options, a treatment index, and a list of everything in our fishkeeping medicine cabinet, natural and commercial (and more!)


    5. Seachem KanaPlex

    Seachem KanaPlex Fungal

    Active Ingredients: Kanamycin
    Diseases Treated: Dropsy, pop eye, septicemia, fin rot
    Number of Doses Required: 3
    Invertebrate Safe: Usage specific

    Seachem KanaPlex is a powerful antibiotic that can treat both bacterial and fungal infections. It is only available in one bottle size that holds 0.18 ounces of medication. It can be added directly to the tank water, but this is not recommended for tanks with invertebrates. In tanks with invertebrates, the manufacturer recommends adding the medication to a food mixture. It is well-absorbed through skin and gills when added to the water for situations where the fish is refusing food. For both uses, the manufacturer recommends using for no more than 3 days. Long term use of this medication can lead to liver damage in your fish. It is a powder that includes a small scoop and is dosed at a scoop for every 5 gallons of water.

    Pros
    • Powerful antibiotic
    • Can treat fungal and bacterial infections
    • Can be added to tank water or used in medicated food
    • Safe for invertebrates when added to medicated food
    • Well-absorbed through skin and gills from water
    • Should see improvement within 3 days
    • Doesn’t tint water
    Cons
    • Only one size available
    • Not cost-effective for large tanks
    • Partial water change required between doses
    • Should not be added to water if invertebrates present
    • Long-term use can lead to liver damage

    6. API E.M. Erythromycin

    API E.M. Erythromycin Freshwater

    Active Ingredients: Erythromycin
    Diseases Treated: Cotton wool disease, skin lesions, bacterial gill disease
    Number of Doses Required: 4
    Invertebrate Safe: Yes

    API E.M. Erythromycin is effective against gram-positive bacteria, as well as some gram-negative bacteria and fungi. This medication comes in a box of 10 packets and a 30-ounce bottle, making this a cost-effective option for small and large tanks. For the packets, this medication is added directly to the tank water and is dosed with a packet for every 10 gallons of water. A 25% water change is recommended between the second and third doses and 24 hours after the fourth dose. It can be used in conjunction with some other medications if needed. It won’t discolor your tank water. This antibiotic is relatively weak compared to some other options, so it may be ineffective against moderate to severe infections.

    Pros
    • Effective against gram-positive and some gram-negative bacteria
    • Available in two package sizes
    • Cost-effective
    • Can be effective against some fungi
    • Can be used with other meds if needed
    • Won’t discolor tank water
    Cons
    • Requires multiple water changes
    • Weak compared to some other antibiotics
    • If no improvement within 4 days, then a different med is needed

    7. Fritz Aquatics Maracyn Two

    Fritz Aquatics

    Active Ingredients: Minocycline
    Diseases Treated: Fin rot, pop eye, dropsy, septicemia, secondary infections
    Number of Doses Required: 5–7
    Invertebrate Safe: Yes

    Fritz Aquatics Maracyn Two is an antibiotic that is effective against gram-negative bacteria but will not treat gram-positive bacteria. It comes in a box of 24 small packets of medication. The initial dose is two packets for every 10 gallons and then 1 packet for every 10 gallons for each subsequent dose for 5–7 days. This medication is on the pricey side and isn’t cost-effective for most tanks, but it is effective for some hard to treat infections. It’s added directly into the tank water and does not require water changes between doses. It also will not discolor your tank water. After the full dosing schedule is complete, a water change should be performed.

    Pros
    • Treats gram-negative bacteria
    • Easy to dose packets
    • Does not require water changes between doses
    • Doesn’t tint water
    Cons
    • Not cost-effective
    • Only available in one pack size
    • Not effective against gram-positive bacteria
    • Water change should be performed after completion of dosing

    8. API Furan-2 Freshwater Aquarium Fish Medication

    API Furan-2 Freshwater Aquarium

    Active Ingredients: Nitrofurazone
    Diseases Treated: Hemorrhagic septicemia, eye cloud, bacterial gill disease, fin rot
    Number of Doses Required: 4
    Invertebrate Safe: Yes

    API Furan-2 Freshwater Aquarium Fish Medication is usually used as a topical antibiotic, so in the case of treating fish, it’s added directly to the water. This medication comes in a pack of 10 packets but is also available in a 30-ounce bottle that can treat large tanks and some ponds. For most tanks, you will administer a packet for every 10 gallons. The manufacturer recommends a 25% water change between the second and third dose, and then another 25% water change 24 hours after the fourth dose. It’s able to treat gram-negative and gram-positive bacteria. This medication will discolor the tank water and should be handled with gloves because nitrofurazone is considered to be possibly carcinogenic, or cancer causing. It has been known to cause tumors in rats and mice and some people are particularly sensitive to this medication and may have skin reactions to it.

    Pros
    • Treats gram-negative and gram-positive bacteria
    • Easy to dose packets
    • Cost-effective
    • Should be effective within 4 days
    Cons
    • Requires multiple water changes
    • Will tint tank water
    • Possibly carcinogenic
    • Some people are very sensitive to this medication

    9. Fish Aid Antibiotics Doxycycline Capsules

    Fish Aid Antibiotics Doxycycline

    Active Ingredients: Doxycycline
    Diseases Treated: Mouth rot, fin rot, septicemia
    Number of Doses Required: 5–10
    Invertebrate Safe: Yes

    Fish Aid Antibiotics Doxycycline Capsules are available in one bottle of 12 capsules of 100 mg medication. It is not a cost-effective option for most tanks. This medication is administered by opening the capsule and adding the contents into the tank. The dosing schedule is 1 capsule for every 15 gallons every 24 hours for at least 5 days. If you are not seeing improvement by day 10, then you may need to consider a different medication. The manufacturer recommends partial water changes between doses of this medication. It’s effective against gram-positive and some gram-negative bacteria and it shouldn’t discolor your tank water.

    Pros
    • Effective against gram-positive and some gram-negative bacteria
    • May see improvements within 5 days
    • Won’t discolor tank water
    Cons
    • Premium price
    • Only available in one bottle and dose size
    • Only 12 capsules to a bottle
    • Requires partial water changes between doses

    10. Fish Aid Antibiotics Clindamycin Capsules

    Fish Aid Antibiotics Clindamycin

    Active Ingredients: Clindamycin
    Diseases Treated: Non-specific infections
    Number of Doses Required: 5–10
    Invertebrate Safe: Yes

    Fish Aid Antibiotics Clindamycin Capsules are an effective broad-spectrum antibiotic against non-specific infections, particularly gill infections. It’s available in 150mg capsules in bottles of 30 capsules, 60 capsules, and 100 capsules. This can be used for an entire tank or as a medicated bath for sick fish. It’s dosed at 1 capsule for every 10 gallons of water and should be repeated for at least 5 doses. If no improvement is seen within 5 days, discontinue this medication. This medication is not cost-effective for large or small tanks and ideally, should only be used if you can’t identify the infection your fish has. It will discolor the water with a yellow tinge and requires multiple water changes during the treatment period.

    Pros
    • Treats gram-positive and gram-negative bacteria
    • Three bottle sizes available
    • Should see improvements within 5 days
    • Can be used in the main tank or as a hospital tank bath
    Cons
    • Premium price
    • Multiple water changes required throughout use
    • May be difficult to know when to use
    • Discolors the water

    Buyer’s Guide – Choosing the Best Goldfish Antibiotics

    Common Bacterial Infections in Goldfish and Their Symptoms
    • Fin/Tail Rot: Often caused by pseudomonas bacteria, fin rot can also be caused by a fungus. It’s characterized by fins with jagged edges, redness, and discoloration. Rule out fin nipping and bullying before treating for fin rot.
    • Septicemia: Caused by various types of bacteria, septicemia is a bacterial infection that has become systemic by entering the bloodstream. It often starts with an open wound or another infection that decreases immunity. It can be deadly and lead to multi organ failure. Hemorrhagic septicemia is caused by a contagious viral infection, but some antibiotics may be effective against it. It can be characterized by red streaks on skin and fins, lethargy, inappetence, and another infection that isn’t improving.
    • Pop Eye: Pop eye in fish is usually caused by an injury, like hitting the eye against a sharp object in the tank. It can be caused by bacterial infections, but usually, antibiotics are used to prevent an infection through the open eye socket while it heals over. Pop eye is characterized by a missing eye or eyeball dangling from the socket.
    • Dropsy: Dropsy is a systemic infection that is the body’s response to other medical problems. Infections can lead to fluid collections outside of the blood vessels, often causing it to pool in the abdomen. Fish with dropsy will have swollen, abnormally rounded bellies and dropsy is characterized by pineconing, which means the fish has become bloated enough for the scales to push out from the body, causing the fish to look like a pinecone.
    • Eye Cloud: Eye cloud is sometimes caused by injury, but if both eyes are affected then it is likely caused by a bacterial infection. Eye cloud is characterized by a white film or cloudiness in or on the eyes.
    • Bacterial Gill Disease: BGD can be caused by an overgrowth of naturally present bacteria in the gills, but it can also be caused by external bacteria. It often leads to swelling or abnormal shaping of the gills, and even can lead to the gills fusing closed.
    • Hexamita: Hexamita, also known as Hole in Head Disease, isn’t caused by a bacterium but can be treated with some antibiotics. Hexamita is a protozoal infection that causes a deep open wound to develop on the face or head.
    • Ich: Not a bacterial infection, ich is one of the most common diseases seen in aquarium fish. It’s caused by a parasite that latches onto the fish’s scales. The parasites will drop from the fish to reproduce in the water. They will then free swim until they find a host. Some antibiotics are effective against this parasite.
    Cons
    • Tank Size: If you have a large tank, it may be far more cost effective for you to use a hospital tank while treating your fish. This will save you money by allowing you to use significantly less medication than you would if you needed to treat an entire large tank. If multiple fish in your tank are showing symptoms of illness, though, then you should treat the entire tank.
    • Aquarium Residents: Some medications aren’t safe for invertebrates, like shrimp and snails, so make sure anything you use is safe for your invertebrates. Sometimes, you can temporarily keep your invertebrates in another tank, but you’ll need to ensure the medication is fully cleared from the tank before adding them back to the main tank.
    • Symptoms: If your fish is sick, try to make a list of all of the symptoms you are seeing, then search these symptoms or call your vet to narrow down the diagnosis. Some antibiotics will work much better for some illnesses than others, so the better you can narrow down the illness itself, the more effective treatments you’ll be able to choose.

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    Conclusion

    The top three antibiotics for your goldfish are Fish Aid Antibiotics Cephalexin Capsules, Fish Aid Antibiotics Amoxicillin Capsules, and Seachem MetroPlex. These medications tend to be the most effective of these product reviews with the fewest cons, but they are not effective for all illnesses. Narrow down your fish’s symptoms to choose the best course of action, then change up the medication if no improvements are noted. If needed, you can always reach out to a fish or agricultural veterinarian near you who may be able to help you narrow down a diagnosis and recommend the best course of treatment.


    Featured Image Credit: mrk3PHOTO, Shutterstock

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