I had the same problem...
I have a 55gl and was fish sitting a tang for a friend while his 120 was cycling. I had the luxury of having no other fish in the tank (other than the 1 yellow tang), but my tank is *full* of newborn peppermint shrimp so moving the rockwork was not an option.
I went to a local bait & tackle shop and purchased a "minnow trap"(your little brother can help you find one
) . it was along the same idea of the 2 liter bottle trap you can make for smaller fish.. it is about 16" long and is made of either fine clear fish mesh or aluminum wire mesh (I avoided the metal ones for fear of accidental copper). The trap has one backwards opening that lets the fish in but not out. Dropped it in, added a block of frozen brine shrimp to entice the fish in... and 30 minutes later the tang was trapped.