Protocols

Step-by-step protocols for bringing new goldfish home and for common treatments. Every dose is given per liter and per US gallon (1 US gallon = 3.785 liters; ppm = mg per liter). Salinity tables and supportive care live on Treatments; one entry per medication lives on Medications.

Quick index

Quarantine · New fish acclimation · Fish shipping · Water cooling · Ich · Flukes · Dips · Salt dip · H₂O₂ dips · KMnO₄ dips & baths · Methylene blue · Epsom baths

Quarantine protocol

Every new goldfish gets a full quarantine — from a trusted seller, a friend, or a show. Never shorten it because the fish look healthy: fish can carry parasites without showing symptoms. Go slow; longer is safer, and some keepers keep each new line in its own system for good.

Before you buy

• Don't bring home fish with sunken, skinny bellies. Fish TB (mycobacteriosis) has no reliable over-the-counter cure and usually comes from dirty systems. Rescues from pet shops and keepers leaving the hobby carry the same risk.
• Have the quarantine tank set up and running before the fish arrive.

Set up

• A separate tank or tub with a heater (secured so fish can't lie on it) and an air stone. Bare bottom, so waste is easy to siphon.
• Its own nets, buckets and siphon. Gear does not move between quarantine and your other tanks until it has been disinfected (bleach recipe on Medications).
• Wash your hands with soap after working in any tank. Disposable gloves are cheap if you have cuts.
• Sponges and filter media from a tank that held sick fish: replace them rather than trying to clean them.

Quarantine without a cycled filter

• Double the dose of water conditioner, and add 0.15% salt (NaCl): 1.5 g per liter ≈ 5.7 g per US gallon, weighed. Salt details: Salt (NaCl).
• Why it works: the conditioner binds up the ammonia (only if it's an ammonia-binding conditioner — check the label for that claim), and the salt, specifically the chloride, protects the fish from nitrite.
• Weekly water changes. Redose conditioner and salt for just the volume of water you replaced, not the whole tank. Example: replacing 4 liters (≈1.06 gallons) needs 6 g of salt; replacing 5 gallons (18.9 liters) needs ≈28.4 g.
• Keep testing ammonia and nitrite. Above zero: change water (what to test for and why).

Why not just use a pre-cycled filter? You can. It's a trade-off: safer for water chemistry, but it's a disease vector for the new fish. Your existing fish can be carrying parasites without showing symptoms.

Treat on arrival, or isolate and watch

• Treat on arrival: the Aquarium Co-op Quarantine Trio (Fritz Maracyn — erythromycin; Aquarium Solutions/Hikari Ich-X — formalin + malachite green chloride; Fritz ParaCleanse — metronidazole + praziquantel). Dose: 1 packet Maracyn + 1 packet ParaCleanse + 5 ml (1 US tsp) Ich-X per 10 US gallons = 0.1 packet of each + 0.5 ml Ich-X per gallon; per liter, 1 packet of each per ≈37.9 L + ≈0.13 ml Ich-X per liter. Remove chemical filtration (such as activated carbon or Purigen), turn off UV, add surface agitation, keep the filter and heater running. Soak 7 days without feeding and without water changes (if you must feed, wait until day 4–5 and feed very lightly), then change 30% of the water and resume feeding. This feeding instruction applies during the soak week; after it, go back to the quarantine feeding below. Weak fish get one med per week instead. Full schedule and cautions: Medications.
• Isolate and watch: fish from sources with a good track record can go through quarantine with no prescribed treatment — isolated, watched closely, and treated only if something shows up.
• Fish with wens (orandas, ranchu): treat for flukes (praziquantel, below) and Hexamita (metronidazole, per label) during quarantine.
• Watch ammonia and nitrite during any treatment: Fritz's ParaCleanse directions say it may inhibit nitrifying bacteria. Never use the trio alongside potassium permanganate (KMnO₄) — Ich-X contains formalin.

Feeding during quarantine

• Feed lightly, every few days, throughout quarantine.
• Exception — the Quarantine Trio soak week: follow Aquarium Co-op's instruction for those 7 days: no feeding; if you must feed, wait until day 4–5 and feed very lightly.

Ending quarantine

• Quarantine ends only when treatment is complete and the fish have stayed healthy afterward. If anything shows up, the clock restarts after that treatment.
• If you only have a few tanks, mix fish slowly: every new fish potentially brings a new set of pathogens to the fish already there, and vice versa.

New fish acclimation protocol

New fish go into the quarantine tank, never straight into a display tank or pond.

1. Prepare the water first. Quarantine water should already be at temperature, aerated and conditioned. On chlorinated tap water, use a dechlorinator that handles chlorine and chloramine; well water may not need one.
2. Dim the lights. Turn off the tank light and keep the room dim to cut stress.
3. Match temperature. Float the sealed bag in the quarantine tank for 15–20 minutes.
4. Mix in tank water slowly, by either method:
   • Cup method: open the bag and add about a cup (≈240 ml) of quarantine water every 5 minutes for 20–30 minutes.
   • Drip method: put the fish and its bag water in a clean container (a fish-only bucket) set below the tank. Run airline tubing from the tank into the container and start a siphon. Control the flow with a loose knot in the tubing or an airline valve, to roughly 2–4 drips per second. Keep dripping until the water volume in the container has doubled or tripled.
5. If the fish look stressed (gasping, lying on their side, not righting themselves), skip the slow mix: once temperature matches, move them.
6. Net the fish into the tank, leaving the bag water behind. Never pour bag or bucket water into any tank — throw it out.
7. Optional salt dip on arrival: fish just home from a store, or coming in from a summer pond, can get a 3% salt dip on the way into quarantine, unless they are very small or have never been in salted water.
8. Leave them alone. No feeding on the first day; lights low; watch for gasping, clamped fins, flashing or lying on the bottom.

Fish shipping protocol

Packing fish to ship. Fish packed this way arrive fasted, in heavily conditioned water, which is why the receiving end doesn't need to rush acclimation.

1. Fast the fish for 2 days before shipping.
2. Use freshly prepared water in the shipping bag.
3. Quad-dose the water conditioner in the shipping water.
4. Fill the bag 1/3 water and 2/3 pure oxygen.
5. Double-bag it. Put the first bag top first (rubber-band end) into the second bag. Once the second bag is banded, there are no corners for the fish to get stuck in.
6. Pack it in an insulated box, either with the inner bag upright or the whole thing on its side.
7. Overnight or 2-day shipping is best; 3-day is OK. USPS Priority Mail is usually 3 days and is fine for well-packed fish. Add a heat or cold pack if needed.
   Anecdotally, in our experience, packages that get delayed or lost in transit tend to still arrive with the fish OK.
8. Larger specimens do better with less time in the bag.

Water cooling protocol

In extreme heat, a clip-on desk fan blowing across the water surface cools the water by evaporation.

• How much it cools depends heavily on humidity. Expect a few degrees, typically 2–4°F (about 1–2°C). In very dry air it can be more, sometimes up to about 10°F (about 5.5°C). It works great in the desert, not in the swamp: in humid air it may barely help.
• Aim the fan over open water. Keep the lid open, or point the fan at an open section of the surface. Clip it securely so it can't fall in.
• Evaporation goes up a lot. Top off with fresh, dechlorinated water, not salt water: salt doesn't evaporate, so topping off with salted water raises the salinity.
• Add aeration. Warm water holds less oxygen.
• Bonus: automate it. A plug-in temperature controller can switch the fan on and off. Inkbird is a good brand: the ITC-308 is a dual heat/cool controller with separate heating and cooling outlets. Plug the fan into the cooling outlet and put the probe in the tank water.

Ich (white spot)

White spots like grains of salt or sugar. The parasite feeds under the skin, where meds can't reach it; treatments work on the free-swimming offspring. Choose one of two options. More on ich: Diseases.

Option 1: Formalin + malachite green

• Use a formalin + malachite green product such as Rid-Ich Plus (Kordon) or Ich-X (Aquarium Solutions/Hikari), according to the manufacturer's instructions. Brands change and get reformulated: check the active ingredients on the label.
• Label example (Ich-X): 5 ml (1 US tsp) per 10 US gallons = 0.5 ml per gallon ≈ 0.13 ml per liter, giving ≈15 mg/L formalin and ≈0.05 mg/L malachite green. Multi-day course, with water changes between doses as the label directs.
• Formalin lowers oxygen: add extra aeration. The products are light-sensitive and toxic; overdoses kill fish. Not for fish with fried (dark red/brown) gills. Never mix with potassium permanganate (fire/explosion risk). Details: Formalin + malachite green.

Option 2: Heat

• Raise the temperature to 85°F (29.4°C) and hold it there for 2 weeks. That is too hot for the ich offspring to survive.
• Raise it gradually: no more than about 2°F (≈1.1°C) per hour.
• Run maximum aeration: warm water holds less oxygen.
• Feeding: feed sparingly during the heat treatment. (The site's feeding chart stops feeding at 85°F (29.4°C) and above, but that's aimed at fish in hot climates where tank water naturally runs that warm, not at a deliberate ich treatment.)
• Know what you are treating for. Heat also speeds up other parasites. If flukes or costia could be present (flashing, gill trouble, a fish that hasn't been through quarantine), deal with them first or use Option 1.
• Match the temperature on every water change. After 2 weeks, cool slowly, about 2°F (≈1.1°C) per day, back to normal.

Either way: disinfect nets and gear after an ich outbreak (bleach recipe).

Flukes

Two rounds of praziquantel: the first kills existing flukes, the second catches the ones that hatch afterward. Praziquantel is preferred over hydrogen peroxide dips for flukes. ID and symptoms: Diseases.

• Dose: 2 mg per liter (≈7.57 mg per US gallon) of veterinary or lab-grade praziquantel (Dr. Erik Johnson). Products such as PraziPro: per label. Full entry: Praziquantel.
• Mixing: the powder is hard to wet. Stir it vigorously into a liter of clean water, then add it to a high-flow area.
• Before dosing: turn off carbon and UV. Fill the tank to the brim — flukes and their eggs collect in the wet band around the rim.
• Schedule — two rounds: round 1 on day 1; round 2, 4–5 days later (Dr. Johnson's repeat dose). Gill fluke eggs hatch in about 4 days near 68–70°F (20–21°C), so the second round catches the newly hatched flukes. Recheck afterward and retreat if flukes persist.
• Skin flukes (Gyrodactylus) are live-bearing and worse in warm water and poor conditions. Light salt (0.1%: 1 g per liter ≈ 3.8 g per gallon, weighed) supports the slime coat.
• Gill flukes (Dactylogyrus) lay eggs: retreat and recheck over weeks. Moving fish bucket-to-bucket helps leave eggs behind. Don't raise heat for bacteria until gill flukes are dealt with.

A 0.01 g jewelry scale helps with small amounts of powder (Starter kit).

Dips

A dip is a brief, strong exposure, then back to clean water. Doses and times match Medications.

Every dip

• Mix the dip in aerated water at the same temperature as the fish's tank — water taken from the fish's own tank is best. Weigh or measure; don't guess.
• Time it and watch the fish the whole time. A fish that rolls onto its side or can't stay upright comes out at once into clean water.
• Back in clean water, fish purge waste and ammonia: test and change water.
• Don't dip very small fish or fry, stressed or ulcerated fish, or fish with fried (dark red/brown) gills from ammonia.
• One dip at a time. Check Do not combine before using anything else in the same water or on the same day.

Salt (NaCl) dip — 3%

• Dose: 30 g per liter ≈ 113.6 g per US gallon — about 3% by weight, not 3 ppm. Weigh it.
• Time: about 30 seconds for a crisis parasite strip, or for small or stressed fish; up to a few minutes for general parasites, and out by 5 minutes even if the fish is still swimming normally.
• Watch: sitting on the bottom is normal. If the fish comes up on its side, nudge it — it should dive. If it doesn't dive quickly, take it out.
• Uses: ich, costia, chilodonella, trichodina, flukes and gill rot, often followed by a multi-day treatment. Also on arrival for new fish.
• Not for: fish that have never been in salted water, or pineconing dropsy (use Epsom salt instead). Don't return the fish to its old tank until that tank is clean or treated.

Hydrogen peroxide (H₂O₂) dips — 3% drugstore solution

Hazard: overdoses, or longer or stronger dips than these, destroy gills. Watch for distress and pull the fish early if it shows any. Don't combine with methylene blue. Details: Hydrogen peroxide.

Potassium permanganate (KMnO₄) dips & baths

• Whole-tank treatment: bypassing the bio-media is best practice but not strictly necessary; run lots of surface agitation; on the last round keep the bio-media in. Watch ammonia and nitrite — the treatment can kill beneficial filter bacteria.
• Dose from a stock solution diluted to the target ppm. The water should stay pink; if it clears right away, organics ate the dose — don't blindly redose.
• Neutralize with 3% hydrogen peroxide, the same volume as the KMnO₄ dose (Medications also lists 1.5 ml per gallon ≈ 0.40 ml per liter to deactivate KMnO₄).
• Hazard: strong oxidizer. Never mix with formalin, including formalin + malachite green products and the quarantine trio — fire/explosion risk. Not on fried gills. Don't combine with methylene blue. Details: Potassium permanganate.

Methylene blue

• Dose: per label. Treats bacteria, fungi and protozoa in the water.
• It damages nitrifying bacteria, so use it in a dip container or a hospital tub without a biofilter, not in a tank with a cycled filter.
• Don't combine with oxidizers such as potassium permanganate or hydrogen peroxide. Details: Methylene blue.

Epsom salt (MgSO₄) baths

Epsom salt is magnesium sulfate, not table salt. These are short baths in a separate container; the same doses, and the small in-tank dose for dropsy, are on Medications. Watch ammonia.