How do I know which fish medication to use?

Start with the symptom, not a guess. White spots and flashing point to a parasite treatment like Parazoryne or Aquascape Parasite and Ich Treatment. Cottony growths mean fungus, which calls for Fungus Treatment, PimaFix, or Sabbactisun. Open sores, ulcers, or fin rot are usually bacterial, which is where MelaFix, Ulcer and Bacterial Treatment, or Sabbactisun come in.

Can I use more than one fish medication at the same time?

Sometimes, but not always on the same day. Parazoryne and Sabbactisun are labeled to be used twelve hours apart if a fish needs both a parasite and a bacterial treatment. Check the label on any two products before combining them, since dosing them together isn't always safe.

Will these treatments hurt my beneficial bacteria or pond plants?

The herbal products (MelaFix, PimaFix, Parazoryne, Sabbactisun) are made from plant extracts and are labeled safe for biological filters, aquatic plants, and invertebrates like snails. Broad Spectrum Disease Treatment is a chemical formula and needs more caution around filtration.

How long does it take to see improvement after treating?

Most courses run five to ten days, and it's normal not to see a dramatic change in the first day or two. Finish the full course even if the fish looks better early, since stopping early is a common reason infections come back.

Do I need to quarantine a sick fish before treating it?

It helps but isn't always required. Treating in a separate tank protects the rest of your fish from whatever's contagious and keeps the medication from disrupting your main pond's biological filter. Some products, like MelaFix, are also labeled for a shorter preventive dose when quarantining new fish before they join the main pond.

Should I turn off my UV clarifier or remove carbon before dosing?

For several products in this category, yes. UV and ozone can break down medication before it works, and activated carbon will pull it straight out of the water. Check the instructions on the specific product, since not every one requires this step.

Are these medications safe for both koi and goldfish?

Yes. Nothing in this category is species-specific to koi or goldfish. A few products list additional caution around fish intended for human consumption or around crustaceans like crayfish, so it's worth checking the label if that applies to your pond.

What if the medication doesn't clear up the problem?

If a fish isn't improving after a complete treatment course, it's worth testing your water before reaching for a second product. Ammonia, nitrite, or pH problems can look like disease and won't resolve with medication alone. Persistent problems are also a sign to get a second opinion rather than stacking treatments.

Fish Meds

Fish medication is what stands between a treatable pond problem and a fish you lose overnight. This category holds the antibacterial, antifungal, and parasite treatments we carry for koi, goldfish, and other pond fish, along with a disease-prevention formula for ponds that haven't shown symptoms yet.

Sick pond fish rarely announce exactly what's wrong. A fish flashing against rocks might have parasites. A cottony patch on the skin usually means fungus. Red streaks in the fins can point to bacteria, parasites, or ammonia stress, and sometimes more than one at once. The lineup here spans natural herbal remedies from Microbe-Lift, all-natural antibacterial and antifungal formulas from API PondCare, and targeted dewormers and disease-specific treatments from Aquascape.

Some of these ship as ready-to-use concentrates you dose straight into the pond. Others target one specific parasite or infection type and work best alongside a water test. If you're not sure which product your fish needs, the guide below breaks it down by what you're actually seeing in the water.

What's Actually in This Category

Eleven products, three brands, four kinds of problems: bacterial, fungal, parasitic, and prevention. That's the fish medication lineup at Puget Sound Ponds, and it's worth knowing what each brand does differently before you reach for a bottle.

Aquascape's Symptom-Specific Line

Aquascape sells four separate treatments, each built around one problem instead of a broad-spectrum blend. Aquascape Ulcer and Bacterial Treatment targets open wounds, ulcers, and bulging eyes. Aquascape Fungus Treatment is for the cotton-ball growths that show up on skin and fins. Aquascape Parasite and Ich Treatment handles the classic salt-like white spots, along with flashing and rubbing against rocks. Aquascape Praziquantel Treatment is a dewormer, aimed at internal and external parasites like flukes, flatworms, and tapeworms. It only takes one treatment with no water changes required, which matters if you're managing a large pond.

API PondCare's All-Natural Pair

API Pond MelaFix and API Pond PimaFix are meant to work together. MelaFix is the antibacterial half, used for eye cloud, mouth fungus, fin and tail rot, and open wounds. PimaFix leans antifungal but also treats internal and external bacterial infections, and API recommends dosing the two in combination for stubborn cases. Both are plant-derived, safe around snails and other invertebrates, and won't touch your pond's biological filter or shift your pH.

Microbe-Lift's Herbal and Chemical Options

Microbe-Lift covers more ground than the other two brands combined. Parazoryne is a natural parasite expellant effective against white spot, costia, flukes, trichodina, oodinium, and chilodonella. Sabbactisun handles bacterial dropsy, fungus, milky skin, and fin rot, and it's designed to be used twelve hours apart from Parazoryne if a fish needs both. Lice and Anchor Worm is exactly what it sounds like: a treatment for external crustacean parasites that nothing else in this category touches. Broad Spectrum Disease Treatment is the one chemical-based option here, formulated with malachite green and formalin for ich, chilodonella, costia, oodinium, trichodina, and fungal infections. TheraP is different from the rest. It's a preventive, meant to support fish immunity and water quality before disease shows up rather than treat it after the fact.

How to Choose the Right Treatment

Match the Medicine to the Symptom, Not the Species

None of these products are koi-only or goldfish-only. What matters is the symptom in front of you, not the species in your pond. Flashing and rubbing point toward parasites, which is Parazoryne, Praziquantel, or Parasite and Ich Treatment territory depending on whether you're dealing with external irritation, internal worms, or ich specifically. Cottony growths mean fungus, which narrows things to Fungus Treatment, PimaFix, or Sabbactisun. Open sores, ulcers, and fin rot are usually bacterial, which is where MelaFix, Ulcer and Bacterial Treatment, or Sabbactisun come in. If you see visible lice or anchor worms attached to a fish, that's the one symptom in this category with only one real answer: Lice and Anchor Worm.

Natural Herbal Remedies vs. Chemical Formulas

Most of what's here is plant and herbal based. MelaFix, PimaFix, Parazoryne, and Sabbactisun are all made from natural extracts, won't harm your biological filter or aquatic plants, and are gentle enough to use during feeding. Broad Spectrum Disease Treatment is the exception, built on malachite green and formalin. It's a stronger option for tougher parasitic and fungal cases, but it isn't something to reach for automatically. Start with the herbal option that matches your symptom, and move to the chemical treatment if that doesn't clear it up.

Read the Dosage Before You Buy

Sizing matters more in fish medication than in most other pond categories. Underdosing a large pond does almost nothing, and overdosing can add stress to fish that are already sick. Praziquantel treats 25 gallons per 5 ml, so a single bottle covers roughly 1,250 gallons. MelaFix covers 4,800 gallons per 16 oz bottle at full-course dosing, with the 64 oz size scaling up from there. Parazoryne and Sabbactisun both come in four sizes, from 8 oz up to a special-order gallon, each rated to treat a specific gallon range for ten days. Match the bottle size to your actual pond volume instead of guessing and buying more later.

Using Fish Medication the Right Way

Prep the Pond Before You Dose

Several of these treatments call for pulling carbon from your filter and shutting off UV clarifiers and ozone units before dosing. Those systems can strip medication out of the water before it has a chance to work. Check the instructions on the product you're using every time, since the prep steps aren't identical across brands.

Course Length Isn't Optional

Most treatments here run a multi-day course rather than a single dose, commonly five to ten days depending on the product. Stopping early because symptoms look better on day two is one of the more common reasons an infection comes back within a week. Finish the full course listed on the packaging, even once the fish looks fine.

Timing and Water Temperature

Fungal and bacterial problems tend to show up around stress: new fish introductions, temperature swings in spring and fall, or an overcrowded pond. Parasite problems often follow the same pattern. Treating early, right when a temperature swing hits or new fish go in, gives these products more room to work than waiting until a fish stops eating.

Quarantine New Fish Before They Join the Pond

New fish are one of the most common ways disease gets into an otherwise healthy pond. A short quarantine period before adding new koi or goldfish, even a few days in a separate tank, gives you a chance to spot a problem before it spreads to fish that are already established. MelaFix is labeled for this exact use, with a shorter three-day preventive dose compared to the seven-day course used to treat an active infection.

Know When One Product Isn't Enough

It's also worth knowing when one product isn't enough. A fish with ich spots and red streaks in the fins may have a parasite problem and a secondary bacterial infection at the same time, since parasites damage the skin and open the door for bacteria. That's a case where a parasite treatment and a bacterial treatment both have a role, though not necessarily on the same day. If a fish isn't improving after a full course of the right treatment, that's the point to get a water test and a second opinion rather than reaching for another bottle and hoping.