Proper acclimation prevents shock from sudden changes in temperature, pH, and water hardness that can stress or kill new fish within hours of introduction.

The simplest method is float-and-release. Float the sealed bag in your tank for 15 to 20 minutes so the water temperatures equalize. Then open the bag, add a small cup of tank water every five minutes for about 30 minutes, and gently net the fish into the tank. Discard the bag water rather than pouring it into your aquarium, as store water may contain pathogens or medications.

The drip acclimation method is more gradual and preferred for sensitive species like shrimp, discus, and wild-caught fish. Place the fish and its water in a clean bucket below the tank. Use airline tubing with a loose knot or a drip acclimation kit to siphon tank water into the bucket at a rate of two to four drips per second. When the water volume has doubled or tripled over 30 to 60 minutes, net the fish into the tank.

During acclimation, keep the lights dim or off to reduce stress. After adding the fish, leave the lights off for several hours and do not feed until the next day. This gives the fish time to explore and settle without additional pressure.

Never dump store water directly into your tank. It may contain copper from medications, elevated ammonia from the transport bag, or parasites and bacteria from the store's system.

Ideally, new fish should go into a quarantine tank for two to four weeks before joining your display tank. This isolation period lets you observe for disease, treat if necessary, and protect your established community from potential infections.