<a href=showthread.php?s=&postid=12397548#post12397548 target=_blank>Originally posted</a> by TorryRx
Quite a few of the experts recommend little to no acclimation as well. Here's the rationale...As the fish excretes ammonia in the bag, it is also increasing the CO2 dissolved in the water. This in turn lowers the pH, which actually makes the ammonia less toxic. But once oxygen is introduced into the bag by opening it, or by dripping water into it the pH raises again making the ammonia toxic. It is better to drop the fish into a different pH than to expose it to the increasingly toxic ammonia.
Sounds good in theory...
Kelly Jedlicki has also done controlled experiments and has found that little/no acclimation has actually slightly improved the survival rate of the fish (I wish I still had that link).
I acclimate to temperature leaving the bag closed (it only takes about as long as it takes me to smoke a cigarette), then in they go. I have had no problems to date.