Drip acclimate. Dump out all but a few inches of water from the bucket, then run an airline down from your tank to the bucket. I use a cheap gang valve turned down to 2-3 drips per second. After a couple hours, you'll want most of the water the fish are in to be your tank water. At that point, scoop them out and dump them in. Don't dump the water in. Watch closely for a few days and check ammonia levels daily.