fill 220.. declor, get temp right... xfer old filter media ect (bio media)to 220... drain 125 down... scoop 'n plop..
unless your moving and the water chemistry will be different this shouldn't harm the fish one bit. Otherwise if you're really worried about the water differences.. run a hose from the old tank to the new.. and drain the old tank down so the water levels are even... and slowly add new water to the bigger tank, in effect drip acclimating them from their old water to "topping off" with new. the trick is making sure the hose stays above the water-lines to keep the syphon going well.
either way should be alot easier on you and the fish. I personally wouldn't sedate a fish unless I had to... but I've never had to move a 16" Dovi before either.
unless your moving and the water chemistry will be different this shouldn't harm the fish one bit. Otherwise if you're really worried about the water differences.. run a hose from the old tank to the new.. and drain the old tank down so the water levels are even... and slowly add new water to the bigger tank, in effect drip acclimating them from their old water to "topping off" with new. the trick is making sure the hose stays above the water-lines to keep the syphon going well.
either way should be alot easier on you and the fish. I personally wouldn't sedate a fish unless I had to... but I've never had to move a 16" Dovi before either.