A quarantine tank is a small, separate, bare-bottom tank where new fish live for a few weeks before joining your display. Reef Builders says to quarantine every new fish, whatever your experience. You need a heater, an air stone, some PVC pipe to hide in and a lid. Top Shelf Aquatics aims for 15 symptom-free days, with any symptoms restarting the count.
Why bother
Disease brought in on one new fish can spread through the whole display, where it’s much harder to treat without harming corals and invertebrates. A quarantine tank keeps that risk outside the main tank.
What you need
Top Shelf Aquatics’ set-up is simple.
- A tank of about 40–150 L; it suggests about 75 L for small fish
- Bare bottom: no sand, so it’s easy to keep clean
- A heater and thermometer
- An air pump and air stone
- PVC pipe or fittings to hide in
- A lid or screen
- Lighting is optional
Observation or treatment
There are two approaches. Observation means watching the fish for a set period and only treating if something appears. Prophylactic treatment means treating every new fish, often with copper, whether or not it shows symptoms.
Top Shelf Aquatics describes a treatment protocol with copper at a measured level and strict testing. Copper is toxic to invertebrates and some fish are sensitive to it, so never use it in a display, follow the product’s instructions exactly, and test it with a proper copper test.
Day to day
Top Shelf Aquatics suggests not feeding for the first three days, then feeding sparingly and removing leftovers. Test ammonia and change water often, because a quarantine tank has little biological filtration. Watch for spots, rapid breathing, cloudy eyes or not eating.
Acclimate into quarantine as you would the display; see how to acclimate corals and fish.
A UK note
Ask your shop whether fish have already been quarantined or treated, and with what. It doesn’t replace your own quarantine, but it helps you plan it.
Common questions
How long should I quarantine marine fish?
Top Shelf Aquatics aims for 15 consecutive symptom-free days. Many keepers quarantine for longer.
Do I need to quarantine corals?
Corals carry pests rather than fish disease. Dipping and inspection are the usual steps.
Can I use copper in my display?
No. It harms invertebrates and builds up in rock and sand.
Sources and limits
Last checked 13 October 2026. Medications can harm invertebrates and some fish. Follow the product’s instructions and get advice from an experienced shop or vet for anything beyond observation.
Keep going
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