A quarantine tank (QT) is the single most effective disease prevention tool. It isolates new arrivals and sick fish, protects your main system, and allows precise medication dosing without harming biofilters.
Why Every Fish Keeper Needs a Quarantine Tank
Un‑quarantined fish introduce 90% of home aquarium diseases — ich, flukes, and bacterial infections. A $100 QT saves you from losing a $500 fish collection.
Essential Equipment for a Fish Hospital Tank
Tank (10–40 gallons) — Bare bottom, no substrate.
Sponge filter — Pre‑seeded in main tank for instant cycle.
Heater with guard — Match main tank temperature.
Thermometer (dual probe) — Monitor tank and QT separately.
Air pump + airstone — Max aeration during treatment.
UV sterilizer (inline) — Controls reinfection during parasite treatment.
Hospital tank lid — Prevents jumping (sick fish are erratic).
Medication mixing station — Reduces dosing errors. Use for marine ich copper treatment.
Common Mistakes in Quarantine Systems
No seeded filter — Ammonia kills the patient faster than the disease.
Using carbon during treatment — Carbon absorbs medication. Remove before dosing.
Skipping the quarantine period — 2 weeks is too short; 4 weeks minimum.
Reusing equipment without disinfection — Bleach soak (1:10, 30 min) between uses.
Recommended Tank Sizes
Small tropical fish: 5–10 gal
Koi / goldfish up to 6″: 20–30 gal
Large koi or pond fish: 40+ gal with extra aeration
Commercial farm: Inline QT system with independent plumbing
How Long Should Fish Stay in Quarantine?
New arrivals: 4 weeks minimum, with prophylactic fluke treatment.
Sick fish with visible disease: Full treatment course + 2 weeks symptom‑free.
After medication: Run carbon for 7 days, then observe for another 7 days before returning to main system.