There are two parts to acclimation and both must be met. The first is temperature. The second is chemistry, as the first will be satisfied if you do the second we will offer only a brief explanation on the first. Temperature is important as most fish can only handle a 3 to 5 degree temp change, less is always better in this case. Chemistry is the most important part of the acclimation procedure. The water chemistry they are kept in here is different than the water chemistry in your tank, also the water chemistry that they are shipped in is always changing over time due to waste and osmoregulation, therefor just floating a bag in your tank is not the correct procedure. Its like jumping in a snow bank naked its shocking and you will most likely get sick. We strongly advise that you acclimate your stock into a quarantine/hospital tank and hold for 5 to 7 days for observation before acclimation (yes, you must do it again) into your show aquarium.