Acclimating Saltwater Aquarium Fish With the Drip Line Method

In this guide

The drip method is the slower, more thorough cousin of the floating bag technique, and most experienced marine hobbyists consider it the safer option, particularly for salinity sensitive fish, invertebrates and anything that has travelled a long distance to reach your tank.

Why drip acclimation is preferred for saltwater

Marine fish and invertebrates are especially sensitive to salinity swings, more so than to small temperature differences. The drip method changes salinity gradually, over sixty to ninety minutes rather than the twenty to thirty minutes typical of the floating method, giving the fish's body time to adjust osmotically rather than being shocked by a sudden change.

What you need

• A clean bucket or container, used only for aquarium purposes.
• A length of airline tubing.
• A way to control drip speed, either a simple knot tied in the tubing, an airline control valve, or a purpose made drip acclimation kit.
• A small amount of premixed saltwater at your tank's salinity, kept on hand to top up water removed during the process.

Step by step

• Dim the room and tank lights before opening the shipping box or bag.
• Check each fish for signs of life and good health before opening any bag; if something looks seriously wrong, photograph it before opening, in case you need to raise it with the seller.
• Pour the fish and its water gently into the bucket, keeping the water level low enough to submerge the fish but not so deep the tubing has to run far.
• Set up a siphon of tank water running into the bucket, using the airline tubing, and tie a loose knot or use a valve to slow the flow to roughly two to four drips per second.
• Let the drip run for sixty to ninety minutes, periodically checking that the fish remains calm and that water is not overflowing the container.
• As the bucket fills, remove and discard some water partway through so the fish is not left in an overfull container, always removing water rather than the fish itself.
• Once the process is complete, net the fish out of the bucket and place it into the tank; never pour the bucket water itself into the aquarium.

A note on quarantine holding tanks

Some experienced reefers deliberately hold new marine fish in a lower salinity quarantine tank for a period after acclimation, since certain parasites, including marine white spot, struggle to survive at reduced salinity. This is a more advanced quarantine protocol on top of, not instead of, careful acclimation, and is worth researching separately before attempting it.

Coral and invertebrate acclimation

Corals, shrimp and snails generally benefit from an even longer, gentler drip, since they are more sensitive to sudden salinity change than most fish and cannot simply be netted out quickly if something goes wrong. For corals specifically, a coral dip is usually done separately, after acclimation, to guard against hitchhiking pests.

Common mistakes

• Dripping too fast, which defeats the purpose of the slow method.
• Leaving the fish in the acclimation container for hours longer than needed, which causes its own stress from a small volume of water and dropping oxygen levels.
• Forgetting to keep the room dim, adding unnecessary stress right when the fish is already vulnerable.

A note on domestic shipping in India

Fish bought online and couriered within India can spend well over twenty four hours in transit, often through hot weather, which lowers oxygen levels in the bag water more than a short local shop to home trip would. If a fish arrives from a long courier journey looking sluggish or is gasping even before acclimation starts, it is worth transferring it into a larger container of matched temperature water with an air stone running before beginning the drip process, rather than starting the drip immediately in the cramped shipping bag.

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