Aquarium · Reef care
Coral & Invertebrate Quarantine Guide
Our fish quarantine timeline calculator is built around fish disease incubation periods, which don't map cleanly onto coral and invertebrates. The risks are different, and so is the protocol. This guide covers what actually matters for a coral or invert going into your display tank.
Why corals need quarantine even though they can't get "sick" the way fish do
The real risk with new coral isn't disease in the fish sense, it's hitchhiking pests. Acropora-eating flatworms, red bugs, nudibranchs, and various snails and worms can arrive on a frag or colony and go unnoticed until they've established a breeding population in your display tank, at which point they're genuinely difficult to eradicate. A dedicated quarantine and inspection period is aimed at catching these before that happens, not at treating an infection the way fish quarantine does.
How long to quarantine
A 4 to 6 week quarantine period is the common standard among experienced reefers, long enough to catch a hitchhiker population's first reproductive cycle, per guidance from Melev's Reef and Reef Builders. Corals typically get dipped on arrival, then watched in a bare, sterile quarantine tank (no substrate or rock for pests to hide in) for the full window before going into the display.
Dip protocols by pest type
A plain freshwater dip, swirling the coral in fresh water matched to display tank temperature and pH for several minutes, is the standard first-line treatment and is effective against flatworms and some soft-bodied pests, which can't tolerate the osmotic shock. It won't touch everything, so most reefers pair it with a commercial iodine-based coral dip (like Coral RX or a similar product) that targets a broader range of pests including Acropora-eating flatworms and red bugs. Follow the product's specific concentration and timing, over-dipping stresses the coral as much as the pest.
Medication sensitivity: the biggest difference from fish quarantine
Invertebrates are far more sensitive to copper-based medications than fish are, copper that's safe in a fish quarantine tank can be lethal to shrimp, snails, crabs, and coral. If you're running a combined fish and invertebrate quarantine setup, or moving equipment between a copper-treated fish QT and a coral QT, treat that cross-contamination risk seriously. Corals and inverts generally need their own dedicated, copper-free quarantine equipment.
What to actually check for during the inspection period
Inspect with a flashlight at an angle, some pests like flatworms and red bugs are easiest to spot under raking light rather than straight overhead. Check the base of the frag plug and the underside of branching structures specifically, that's where pests most often hide. A few nights of lights-off inspection with a flashlight can also catch nocturnal pests that hide during the day.
See our fish quarantine timeline calculator for fish-specific quarantine windows, or the live rock curing calculator if you're setting up rock before adding coral.