Well this seller is opinionated….

[AJ356]

I personally believe it makes a lot of difference in how long the fish have been in the bag, and how different your home aquarium water is from the tank water the fish came from… if there is a huge Ph, or hardness difference… and we would like to think the fish were coming from water parameters that they find natural, and that our water at home is the right parameters , but often neither is true… then slowly adjusting may be needed for a fishes survival…

I typically prepare everything needed, before I cut the bag open, and as soon as I open the bag, I add as much tank water the fish is going into, as I can to the bag, to blend temperature differences and water parameters… I do this in a dedicated dish pan, I freshly pre rinse the net for that tank, and after a minute or two of acclimation, only the fish goes into the tank… the blended bag water goes from the dishpan to the toilet… I can say, that I’ve rarely lost a fish, that wasn’t doa, due to acclimation issues, since I got my home tank water straightened out

Same really, only takes a bit of effort.

 

[GaryE]

It has very little to do with the tank water at home, unless you are really not thinking it through. You have to assume that if you buy a rainforest tetra, you have realized it needs rainforest-ish tetra water. That doesn't have to be exact, but in the survival range.

After a short trip, we either have the right water after doing our homework, or we don't and it's an experiment to see if the fish can adjust. Personally, after almost having my eyebows burnt off my ammonia when opening delayed in transit commercial shipments, I want the fish out of the travel water as quickly as possible.

Drip acclimation seems important with shrimp, from what I hear. With fish, it usually isn't harmful, and probably isn't the least bit useful. I put a net over a bucket. I pour the bag through the net. I put the fish in the tank. Repeat, do it again. If the bagwater is cooler than the tank, I don't wait. If it's warmer, then I float for as short a time as I can and use an infrared temp gauge to check.

Whichever technique you use, I hope you've bought healthy fish. That's the crucial thing we take for granted, and maybe shouldn't.

 

[sharkweek178]

This is a new eternal debate.

It gets passionate and swings to extremes. I don't drip acclimate, and I don't let bag water into the tank. I've never lost fish to acclimation.

If I were an online seller, I'd like cards like that. They'd save you so much trouble with freshwater fish.

Same. I'm plop and drop all the way. I want them out of that bag that they've filled with ammonia and stress pheromones and into their new home with good water and places they can hide until they calm down ASAP.

 

[Magnum Man]

I also do the same procedure for shrimp, & haven't lost any of those due to transfer stress...

 

[Naughts]

As @Fishfunn alluded to, the big risk in adding water to the bag is it can convert relatively harmful ammonium (in acidic water) into highly toxic ammonia (in basic water). Recommending a method that adds water to the bag water without explaining this risk nor offering ways to avoid it is gambling with the lives of the fish.
Coupled with the fact that fish cannot quickly (nor slowly with very few exceptions) acclimate to unsuitable parameters, plop and drop is by far the superior method.

 

[sharkweek178]

As @Fishfunn alluded to, the big risk in adding water to the bag is it can convert relatively harmful ammonium (in acidic water) into highly toxic ammonia (in basic water). Recommending a method that adds water to the bag water without explaining this risk nor offering ways to avoid it is gambling with the lives of the fish.
Coupled with the fact that fish cannot quickly (nor slowly with very few exceptions) acclimate to unsuitable parameters, plop and drop is by far the superior method.

You actually answered a question I've had for a long time. I've always heard people say to not dump the fish store water into your tank. And I have always followed that advice. Because people always said it was to avoid disease. But I also wondered. If there's a pathogen in the water, then wouldn't it be in the fish too? The reason you give here makes more sense.