Marine Fish Health: Quarantine and Disease Prevention

Quarantine Everything

Adding fish straight to a reef without quarantine is the most common way to lose an entire stocking. It's tempting to skip, but one infected fish can wipe out a display tank.

The Quarantine Tank Setup

60-litre tank — bare bottom, no sand, no live rock
Heater — match display temp
Sponge filter — seed it in the sump beforehand
PVC pipe or ceramic pots — hiding spots
Total cost: £50–100 secondhand

The Big Three Diseases

Marine Ich — White spots like grains of salt. Fish scratch against rocks ("flashing"). Copper (Cupramine) works but kills corals and inverts — treat in QT only. If ich enters the display, all fish need removal and the tank must run fishless for 76 days.

Marine Velvet — Finer dusting, rapid breathing, can kill within 48 hours. Requires immediate copper treatment in QT. A genuine emergency.

Clownfish Disease (Brooklynella) — Mucus coating, skin sloughing, rapid decline. Treated with formalin baths. Another reason to quarantine all new clownfish.

Quarantine Protocol

New fish goes in QT — observe for a week minimum
Many reefers run prophylactic copper (Cupramine) or PraziPro regardless of apparent health
Tank Transfer Method (TTM) — copper-free alternative. Move fish between sterile containers every 72 hours for 4 transfers
4–6 weeks total observation before moving to display

Spotting Problems Early

Flashing (scratching against rocks)
Rapid breathing
Colour changes — darkening, fading, or spots
Loss of appetite
Hiding more than usual

Buying Healthier Fish

Fish from hobbyists who've kept them for weeks or months are lower risk than freshly imported specimens. A fish already eating prepared food has survived the danger period.

What quarantine protocols are working well for other UK reefers?