How to Acclimate New Fish Properly
Bringing home new fish is exciting — but proper acclimation is critical to prevent shock, stress, and loss. Sudden changes in temperature, pH, or water chemistry can be deadly.
Follow this simple step-by-step guide to safely introduce your new freshwater fish.
🌡️ Why Acclimation Matters
Fish are sensitive to changes in:
- Temperature
- pH
- Hardness (GH/KH)
- Total dissolved solids (TDS)
- Ammonia levels
Even small differences between bag water and tank water can cause stress, weakened immunity, or death if fish are transferred too quickly.
🪜 Step-by-Step Acclimation Method (Recommended)
🥇 Step 1: Float the Bag (15–20 Minutes)
- Turn aquarium lights off
- Float the sealed bag in your tank
- Allow temperature to equalize
📌 Do NOT open the bag yet.
🥈 Step 2: Open & Start Drip Acclimation
- Open the bag and roll the top down so it floats upright
- Use airline tubing to drip tank water into the bag
- Tie a loose knot in tubing to control flow
💧 Aim for 2–4 drops per second.
🥉 Step 3: Double the Water Volume
- Allow bag water to double in volume
- This usually takes 30–45 minutes
- For sensitive species (killifish, shrimp, wild fish), take 60+ minutes
🐠 Step 4: Net & Transfer
- Gently net fish into aquarium
- Discard bag water (do NOT pour into tank)
⏱ Quick Acclimation (Hardy Fish Only)
For hardy species like:
- Zebra Danios
- Guppies
- Mollies
You can:
- Float bag 15–20 minutes
- Add small cup of tank water every 5 minutes (3–4 times)
- Net and release
🚨 Important Tips
✔ Lights off for first few hours
✔ Do not feed immediately
✔ Expect hiding behavior
✔ Test water parameters beforehand
✔ Secure lid (many fish jump when stressed)
❓ FAQ
How long should acclimation take?
30–60 minutes for most freshwater fish.
Is drip acclimation necessary?
Highly recommended for sensitive or expensive fish.
Can I just float and dump?
No — this risks pH and osmotic shock.