I believe the whole acclimation thing is highly over-rated, and odds are there was something wrong with them in the first place.
My #1 objective when I get a fish (especially a shipped fish) - is to get them out of a bag of ammonia. My logic is multi-faceted...
1) Gee, let me slowly get you out of that poisonous water - as slow as possible so I don't "shock" you. (even in a bag a short time, you would be surprised how quickly ammonia can gather - fish excrete ammonia through breathing as well as through their digestive track).
2) Gee, you seem all stressed in that little bitty bag - stay there a while longer and look at all of this freedom you will soon have and all the places you can escape to when you finally get free so you can calm down (As an avid trout fisheman, one thing that kills the most fish in catch-and-release is the huge build-up of stress-related lactic acid the fish builds up in his blood, so the idea is to catch them faster, and let them go sooner - this is also a reason a lot of exporters will "tranqilize" the fish to reduce their stress of being bagged up in their own poisons)
3) Lastly, as an avid fisherman - anyone who's been in Rivers and lakes knows that the temperature and pH in both rivers and lakes vary greatly even within several feet of various places. I've never asked a fish if it "tests" the water differences by sticking in a "fin" into the flow above it to test the pH or temperature - before it decides to move to the next spot...
Now, all of this, of course (especially temp) is within reason - but there's documented literature (by Axelrod, IIRC) of where the Rio Negro flows into the larger tribs of the amazon where both the temp and pH are significantly different and Discus and Tetras freely flow between the two without "testing ala fin".
As I said, my #1 goal is to get the fish out of a small posionous prision (where his stress compounds the poisoning).
That's my story, and I'm sticking too it.