About a week before, add salt to your tank at a rate of 2-5g/L and Vitamin at a rate of 5-10mg/L.
The day prior, fast your fish.
On the day, siphon water into buckets and place your fish in it.
Turn off the heater and filter, and then remove as much of the aquarium furnishings, water and gravel to allow you to move the aquarium.
Make the move.
Refill the aquarium with conditioned water and the buckets of water you had saved, and replace all aquarium furnishings, and equipment. Turn on your heater and filter.
Float your fish in bags similar to when you first purchase a fish to equalise temperatures over 5-10 min.
Add aquarium water to your bag, waiting another 5-10 min and then release your fish; starting with the smallest, least aggressive species.