Setup path, stage 8
A reef tank quarantine plan you will actually follow
One sick fish can take out a whole tank, and a fish with white spot cannot be treated in a reef full of invertebrates. Set up your quarantine before you buy your first fish, while the main tank is still empty.
Last checked . How we check
What do you need for this stage?
- A small tank (BRS suggests about 20 US gallons, roughly 75 litres), bare bottomed
- A heater, a thermometer and a small filter or air stone
- Pipe sections or similar hides
- Spare salt water at the main tank's salinity
Do I really need to quarantine fish?
Reef Builders lists skipping quarantine and dips as one of the top beginner mistakes. Many keepers still skip it: in one forum poll only 8 of 22 always quarantined. A realistic plan you follow beats a perfect one you skip.
What are my quarantine options?
| Option | What it means | Good for |
|---|---|---|
| Buy pre-quarantined | A shop or supplier has held and watched the fish. Ask what they did and for how long. | Beginners who cannot run a second tank |
| Observation | Hold the fish alone in a small tank and watch for about 30 days before it joins the reef. | Most hardy first fish |
| Full quarantine with treatment | Observation plus a set treatment course. BRS describes several, including a 15-day copper protocol. | Wild-caught and disease-prone fish |
BRS quotes about 15 days of quarantine but also says to observe for at least 30 days, and does not reconcile the two. We suggest at least 30 days of watching. For corals, BRS describes a dip, about 14 days apart, and a second dip (typical): dips do not kill eggs.
How do I set up a quarantine tank?
Run it bare, with hides, a heater and an air stone or small filter. Seed the filter with a sponge that has sat in your main tank's sump for a couple of weeks, or with bottled bacteria, and check ammonia daily while a fish is in it. Match salinity and temperature to the main tank so moving the fish is easy.
What are the steps, in order?
- Choose your level: pre-quarantined, observation or full quarantine.
- Set up the quarantine tank and seed its filter.
- Match salinity and temperature to the display.
- Write down what you will watch for: breathing, eating, spots, scratching.
- Plan how you will move the fish into the display after 30 days.
Your checklist
Tick items as you go. Ticks are saved in this browser only and fill the depth gauge.
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What test must pass before moving on?
Before the first fish arrives:
- The quarantine tank holds temperature and salinity for a week.
- Its filter clears ammonia (a small ammonia dose reads zero after 24 hours).
- You know how long each fish will stay and what you will look for.
What are the common mistakes?
- Setting up quarantine only after a fish is already ill.
- Mixing new fish straight into the display "just this once".
- Treating fish in the display with medicines that harm invertebrates.
- Moving a fish out of quarantine before 30 days because it looks fine.
Where do sources disagree?
| Topic | What sources say | Our reading |
|---|---|---|
| How long |
| At least 30 days of watching. |
| Treat or observe |
| Observe hardy tank-bred fish; consider treatment for wild-caught fish, with a vet's advice in the UK. |
Sources
Figures from sources read as a search summary only are shown as typical figures: check them before you rely on them. Found a mistake? Tell us how to fix it.