if you got this 47 gallon tall from petsmart or petco or a chain retailer i would not bother trying the silvertip shark. the dimensions on the 47tall i am thinking of provide almost no surface area and by the same token, no bottom area meaning the silvertip will get huge and have very little room to swim around the bottom, hell have to swim up and down and it seems like that might spook a lionfish. youre welcome to try but i probably wouldnt.
as far as converting him to salt, i would put him in a cooler or bucket in freshwater and then get a piece of airline tubing. put a slight knot at one end and drop it in the bucket and put the other end in your sw tank and start syphoning tank water into the cooler/bucket. over a couple hours you should be ok i would think.
