Once you open the bag, it's recommended to add Prime to neutralize any ammonia present - just dilute in some tankwater first
I use a 5in1 test strip to quickly compare bag vs tank water (or enquire of shop) ... if pH, GH, KH are similar, I just net & add to tank as this is much less stressful than the "fish in a bag" scenario
Note that before adding new fish (I'm assuming you don't have a quarantine tank)
- 50% water change
- lights off
- reduced CO2
Drip acclimation should be done with aeration & very dim lighting, also avoid vibration/looming shadow stress - floating plant etc cover is helpful
If new fish arrive in stressed condition, I leave lights & CO2 off at least 1-2 days (assuming there's sufficient ambient light to observe new fish)
If there are dead/nearly dead fish in the bag, best action is to remove fish from that environs as soon as possible
Again if I know the water conditions of the shipping agent, I'll have prepped some tap water to match
If fish water condition is unknown, I'll still pour off fish into net & add to a clean bucket etc with tank water & Prime, then add air stone etc
Worry about separating out dead fish after
Then consider if these fish are best kept isolated or added to (community) tank
riverside is another store. Always drip acclimate for best results imo
