Reef Tank Quarantine Setup: 5 Key Steps

Setting up a dedicated quarantine tank is the single most important step you can take to protect your reef tank from disease and parasites. I’ve learned this lesson the hard way, losing entire tanks to ich and velvet because I skipped quarantine. Now, every new fish goes through a strict 30-day quarantine protocol. Here’s my exact setup and process.

Why Quarantine Is Non-Negotiable

New fish often carry diseases like marine ich (Cryptocaryon irritans), velvet (Amyloodinium ocellatum), or brooklynella. In a display tank, these pathogens can spread rapidly, killing fish before you can treat them. A quarantine tank lets you observe, treat, and ensure the fish is healthy before introducing it to your main system. It also reduces stress for the new fish, as it can acclimate without competition from established tank mates.

My Quarantine Tank Setup

I use a 20-gallon long tank for most fish up to 4 inches. For larger fish, I use a 40-gallon breeder. The tank is bare-bottom with no substrate, rock, or live rock. Instead, I use PVC pipes and fittings as hiding spots. This makes it easy to clean and observe the fish. Here’s the equipment list:

• Tank: 20-gallon long (30x12x12 inches) or 40-gallon breeder.
• Filtration: A hang-on-back (HOB) filter rated for 2-3 times the tank volume, plus a sponge filter for biological filtration and extra aeration.
• Heater: 100W adjustable heater set to 78°F.
• Lighting: A simple LED light on a timer for 8-10 hours per day to reduce stress and allow observation.
• Cover: A mesh lid or glass canopy to prevent jumping.
• PVC hiding spots: 1-2 inch diameter PVC elbows and T-joints.

I cycle the quarantine tank with a sponge filter from my display tank’s sump, so it’s ready when needed. If you don’t have a cycled sponge, you can use bottled bacteria and ghost feed with fish food to establish a cycle. Test ammonia and nitrite daily and perform water changes as needed.

Quarantine Protocol Step by Step

Day 1: Arrival and Acclimation

When the fish arrives, I float the bag in the quarantine tank for 15 minutes to equalize temperature. Then I open the bag and slowly add small amounts of tank water over 30 minutes. I never add bag water to the tank. I net the fish and place it in the quarantine tank. I do not feed for the first 24 hours to allow the fish to settle.

Days 2-7: Observation and De-Worming

I observe the fish for signs of disease: flashing, scratching, rapid breathing, white spots, cloudy eyes, or frayed fins. I also start a de-worming treatment with praziquantel (PraziPro) to eliminate internal flukes. I dose according to the label and repeat after 7 days. I feed a varied diet of high-quality frozen foods (mysis, brine shrimp, spirulina) soaked in vitamins and garlic to boost immunity.

Days 8-14: Prophylactic Treatment for Ich and Velvet

Even if the fish looks healthy, I treat with copper-based medication (Copper Power) at therapeutic levels (2.0-2.5 ppm). I use a Hanna copper checker to monitor levels daily. Copper is toxic to invertebrates, so this is only done in the quarantine tank. I keep copper levels stable for 14 days. Alternatively, I can use hyposalinity (1.009-1.010 specific gravity) for 30 days, but copper is more reliable for ich and velvet.

Days 15-21: Observation Period

After copper treatment, I do a large water change (50%) and add activated carbon to remove residual copper. I observe the fish for another week. If no signs of disease appear, I proceed to the next step.

Days 22-30: Final Observation and Transition

I continue feeding and observing. If the fish is eating well, active, and shows no signs of disease, I begin the transition to the display tank. I do a 30-minute drip acclimation into a bucket of display tank water, then net the fish into the display tank. I never add quarantine water to the display.

I recommend starting with budget gear unless you quarantine frequently. The most important investment is a reliable copper test kit.

Common Mistakes to Avoid

• Skipping quarantine: Even from reputable sources, fish can carry diseases.
• Using live rock or substrate: They absorb medications and make it hard to observe fish.
• Not monitoring copper levels: Too low is ineffective, too high kills the fish.
• Shortening the quarantine period: 30 days is the minimum. Some diseases have longer life cycles.
• Adding fish directly to display after quarantine: Always acclimate to display water parameters.

Recommended Products

After years of trial and error, these are the products I trust for my quarantine setup.