| What It Is | Easing a new fish into your water |
| Adjusting For | Temperature, salinity, pH |
| Time | 15–60 minutes |
| Best Method | Float then drip acclimate |
| Golden Rule | Never dump bag water in your tank |
Overview
A new fish has been sitting in bag water that differs from your tank in temperature, pH, and salinity. Dropping it straight in shocks it; so does taking too long with the lights on and ammonia building in the bag. Acclimation is the short, careful process of matching the fish to your water and moving it over — without introducing the store’s water to your system.
Step-by-Step
- Float the sealed bag in the tank (or QT) for 15 minutes to equalize temperature.
- Drip acclimate: open the bag into a small container and run a slow siphon drip from the tank, over 20–40 minutes, until the volume roughly doubles — this gently matches pH and salinity.
- Net the fish out and place it in the tank — net, don’t pour, so bag water stays out of your system.
- Discard the bag water. It can carry disease, ammonia, and copper.
- Keep tank lights off for a few hours so the new fish settles without being harassed.
Tips
Ideally the “tank” you acclimate into is your quarantine tank, not the display. Keep the process calm and reasonably quick — dragging it out for hours lets ammonia build in the container. Sensitive species (angels, anthias, wrasses) especially benefit from an unhurried drip and a dark, quiet first night.
Common Mistakes
Pouring bag water into the tank: the cardinal sin — it can introduce parasites and copper. Acclimating under bright light: stresses an already-stressed fish. Skipping acclimation on “hardy” fish: even tough fish suffer from a sudden pH or salinity jump.
Related Guides
Why You Need a Quarantine Tank
Frequently Asked Questions
How do I acclimate a new saltwater fish?
Float the sealed bag to match temperature for about 15 minutes, then slowly introduce tank water over 30 to 60 minutes (drip acclimation is gentlest), and net the fish into the tank. Never pour bag water into your system.
Should I acclimate to salinity?
Yes. If your tank and the store water differ in salinity, slow drip acclimation lets the fish adjust gradually. A big, sudden salinity swing is a major acclimation stressor.
Why should I not add the bag water to my tank?
Bag water can carry parasites, disease and pollutants. Always net the fish out and discard the water, ideally into a quarantine tank rather than your display.