You can sometimes go lighter, but be careful -- I had #20 wire get WRECKED on a pike in northern Canada last summer. Shredded almost every strand of 7x7. It was a very solid pike, but still.
I really shouldn't laugh, but a few years ago, I had a little 3'er of a tiger musky damn near bite through my 0.018 7x7 (if that were any fluoro, there's no way I would have landed that fish) I didn't notice until I netted it and there were probably 1/3 of those little wires intact! And it didn't appear to be hooked deeply either (those little teeth on the roof of their mouths can wreak havoc on any leader). I honestly couldn't stop laughing at the time....and I was by myself.
I do feel like it's almost always those little ones that just destroy the bite leaders....they're just so much more spastic....in general.
