Bringing a new fish home - what to do

[DanioFish03]

When you bought your new fish, it will obviously be in a plastic bag filled with water. When you bring it home, don't immediately cut the bag open and let your fish go. That will stun the fish from the water change and pressure.
To prepare your fish correctly, leave it in the bag and let it float on the surface of the water. Leave the fish float on the surface for about 30 mins, or a half hour.
When 30 mins. went by, you can cut the bag open and let your new fish swim freely. Just remember to NOT let it free in your tank right away. It needs to get used to the water. Be aware of this or your fish may die!

 

[jetajockey]

Many people now utilize a method called drip acclimation. With some species its mandatory for a safe transition.

 

[jondamon]

It's not just the temperature fish need floating for.

You should also after floating for 30-60minutes pour very small amounts of your tank water into the bag and continue doing this over approx 1-2hours to acclimate the fish to your water parameters too.

Something else to consider doing is not allowing the fish water from the bag into your tank.

I tested my LFS water once when I brought fish home and it was Amm 0 Nitrite 0 Nitrate +80.

Jon