Coral Dipping and Quarantine

Why new corals are dipped and quarantined: the pests and hitchhikers they carry, the dip-rinse-inspect procedure, removing the frag plug, and an observation period before the display.

Overview

Every new coral can carry pests, their eggs, or disease into an established reef tank, and once introduced these pests are very hard to remove. Dipping and quarantining new corals before they go into the display is the standard precaution. Dipping uses a short chemical bath to dislodge or kill hitchhikers, while quarantine holds the coral in a separate system long enough to detect anything the dip missed.

Pests and hitchhikers

Common coral pests include Acropora-eating flatworms (AEFW), Montipora-eating nudibranchs, red bugs (small parasitic copepods on Acropora), zoanthid-eating nudibranchs and spiders, and the pest anemones Aiptasia and Majano. Many of these are small and well camouflaged, and their eggs are often laid in the crevices of the frag plug or base. A single overlooked colony or egg packet can seed an infestation that damages many corals.

Coral dips

Coral dips are concentrated solutions in which a coral is briefly bathed to make pests release their grip or die so they can be rinsed away. Hobby dips include iodine- or oxidiser-based products and insecticide-based dips; they are used at the dose and time stated for the product, with the coral then rinsed in clean tank water. Dips stun or remove many mobile pests but do not reliably kill eggs, which is why dipping is paired with quarantine.

The procedure

• Remove the coral from its frag plug or rock base, since pests and eggs hide in the holes and crevices.
• Bathe the coral in the chosen dip for the recommended short time, swishing gently.
• Rinse the coral in clean saltwater, using a pipette or baster to blow off dislodged pests.
• Inspect the coral closely, ideally under bright or blue light, for remaining pests or egg packets, and mount it on a clean new plug.

Quarantine and observation

After dipping, the coral is best held in a separate observation or quarantine system rather than added straight to the display, so any surviving pests or hatching eggs are caught away from the main tank. Because some pest eggs are not killed by a single dip and hatch later, a quarantine of several weeks, with repeat dips, is recommended for pests such as AEFW so that newly hatched stages can be removed before the coral joins the display.