Why You Need a Quarantine Tank

Why You Need a Quarantine Tank

What It Is A separate tank for new fish
Size A simple 10–20 gallon works
QT Period 2–4 weeks observation
Prevents Ich, velvet, brooklynella, flukes
Golden Rule Quarantine EVERY new fish

Overview

A quarantine tank (QT) is the most important piece of “equipment” a reefer can own, and the most skipped. It’s a simple separate tank where new fish live for a few weeks before joining your display, so that any disease they carry shows up in isolation — where it’s cheap and easy to treat — instead of in your reef, where it’s a catastrophe. Nearly every wipeout story starts with “I didn’t quarantine.”

Why It’s Worth It

You cannot medicate a reef display — copper and most treatments kill corals and inverts. So if ich or velvet enters your reef, your only options are tearing every fish out to treat, or watching them die. A QT stops that at the door. It also lets you fatten up and settle a new fish, and treat for common parasites preventively, before the stress of a community tank.

Setting One Up

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  1. A bare 10–20 gallon tank with a heater, a sponge filter (pre-seeded from your display for instant biology), and some PVC pipe for hiding places.

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  2. No sand or rock — bare bottom is easy to clean and doesn’t absorb medication.

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  3. Match temperature and salinity to your display for easy transfers.

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  4. Observe new fish 2–4 weeks; treat if anything appears. Many hobbyists run a preventive copper or tank-transfer course regardless.

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  5. Only move a fish to the display once it’s eating well and clearly healthy.

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Common Mistakes

“This fish looks healthy, I’ll skip it”: ich and velvet incubate invisibly — healthy-looking is exactly how they get in. No seeded filter: an un-cycled QT spikes ammonia — keep a sponge filter running in your sump so it’s always ready. Treating the QT like storage: it’s observation and treatment, not a holding bucket — keep water quality up.

Related Guides

Marine Ich (White Spot Disease): Identify & Treat · Marine Velvet: The Fast Killer · Brooklynella (Clownfish Disease) · How to Acclimate New Fish