How to Acclimate Fish and Invertebrates to Your Aquarium

Bringing new fish or invertebrates home is exciting — but how you introduce them to your tank can make all the difference in their survival and long-term health. Proper acclimation reduces stress and helps your livestock adjust gradually to differences in water temperature, pH, and salinity. Here's how to do it right.

General Fish Acclimation

1. Float bags for 10–15 minutes to equalize temperature.
2. Open the bags.
3. Add 1–2 oz of tank water (about a shot glass) to the bag every couple of minutes until the water volume doubles.
4. Once doubled, drain half the water from the bag.
5. Continue adding 1–2 oz of tank water until the volume doubles again.
6. Net your fish and add them to your tank. Discard the bag water — do not add it to your tank.

Drip Acclimation for Sensitive Fish and Invertebrates

This slower method is best for corals, shrimp, and other sensitive animals that need extra care.

1. Float bags for 10–15 minutes to equalize temperature.
2. Open the bags and transfer the livestock and bag water into a clean bucket or bowl.
3. Start a drip acclimator siphon set to 3–5 drops per second from your tank.
4. Allow the water level in the container to double.
5. Drain out half the water.
6. Allow the water level to double again.
7. Net your fish or invertebrates and add them to your tank. Discard the container water.

Acclimation Tips

• Turn off aquarium lights during acclimation and for the rest of the day to reduce stress.
• Rearrange decor when introducing fish to aggressive tank mates to disrupt established territories.
• Don't open bags early — if there's a delay, leave the bags floating closed in the tank with lights off.

Need acclimation supplies? Shop our aquarium supplies collection for drip acclimators, buckets, and more.