How to Acclimate New Fish

Why Acclimation Matters

When you buy fish, they come in water that may be significantly different from yours — different temperature, pH, hardness. Dropping fish directly into very different water can cause osmotic shock or temperature shock, both potentially fatal.

Method 1: Float Method (Simple)

Adjusts temperature only. Suitable for hardy fish and small pH differences (less than 0.5 pH units).

1. Turn off tank lights to reduce stress.
2. Float the sealed bag for 15-20 minutes to equalize temperature.
3. Open the bag, add a cup of your tank water.
4. Wait 5 minutes, add another cup. Repeat 2-3 times.
5. Net the fish out and release into your tank. Discard bag water — do NOT pour shop water in.

Method 2: Drip Acclimation (Recommended)

The gold standard for sensitive species, freshwater shrimp, and significant pH differences.

1. Pour the fish and bag water into a clean bucket.
2. Place airline tubing from your tank into the bucket. Tie a loose knot to control flow to 2-4 drips per second.
3. Let it drip until the water volume doubles or triples (30-60 minutes).
4. Discard half the water if the bucket gets too full.
5. Net the fish and transfer to your tank.

Pro Tip: Always drip-acclimate freshwater shrimp (cherry, Amano, crystal). They are extremely sensitive to parameter changes and can die from small pH swings.

Post-Acclimation Tips

• Dim the lights for the first few hours.
• Don't feed for 12-24 hours. Let them settle in.
• Watch for aggression from existing fish.
• Monitor water parameters daily for a week.

Important: Never add shop water to your tank. Shop tanks may contain parasites, medications, or diseases.