Bringing home a new marine fish is one of the most exciting moments in the reef-keeping hobby — and one of the most critical. Proper acclimation dramatically reduces stress, prevents osmotic shock, and sets your new fish up for a long, healthy life in your aquarium. Follow this guide every time you add livestock to your tank.
Why Acclimation Matters
Fish collected or shipped for the aquarium trade travel through significant swings in water chemistry — temperature, salinity, and pH can all shift during transit. Dropping a bagged fish directly into your display tank is one of the fastest ways to stress or kill it. The goal of acclimation is a slow, controlled transition between the bag water and your tank water.
What You'll Need
- Clean bucket or acclimation container (5 gallon works well)
- Airline tubing and a control valve (or a drip acclimation kit)
- Aquarium thermometer
- A small fishnet or specimen container
- Dim lighting — bright light adds stress
Step-by-Step: Drip Acclimation
Drip acclimation is the gold standard for marine fish. It allows you to slowly equalize chemistry over 45–90 minutes, which is gentle enough even for sensitive species.
- Float the sealed bag in your sump or a bucket for 15 minutes to equalize temperature. Do not open the bag yet.
- Open the bag and pour the fish and bag water into your acclimation bucket. Discard excess bag water if volume is large — you don't want to introduce pathogens.
- Set up a drip line from your display tank or sump using airline tubing. Tie a loose knot in the tubing or use the control valve to achieve a drip rate of 2–4 drips per second.
- Drip until the bucket volume doubles — this typically takes 45–60 minutes. For more sensitive species like tangs, extend to 90 minutes.
- Remove the fish with a net and gently introduce it into your display tank. Avoid pouring bucket water into your system — it may contain ammonia or pathogens from shipping.
Tips for Success
- Keep the room dim and minimize noise around the acclimation area.
- Don't rush — slow is always better with marine livestock.
- Have a quarantine tank (QT) ready. Running new fish through a 2–4 week QT before adding them to your display is best practice and protects your existing livestock from disease.
- Check your display tank parameters before introducing anything new. Ideal reef parameters: salinity 1.025–1.026, temp 77–79°F, pH 8.1–8.3, ammonia 0, nitrite 0.
Ready to Add New Fish?
Browse our curated selection of marine fish — all hand-selected for health, color, and reef compatibility. Have questions about a specific species? Reach out and we're happy to help you choose the right fish for your system.