Notonectid

If you are breaking 8 lb leader on 16" fish then you have rotten leader, poor knots tied or "wind knots" in the tippet. Wind knots can reduce breaking strength by 50% or more. On still waters we often tend to try longer casts with the result that a poor cast can result in a wind knot that you might not notice until the leader pops and you notice a little curl in the leader where the knot used to be. Check your leader by tying the tippet to a solid object then pointing the rod at the tight line and then raising the tip as in trying to break the leader. With 8 lb tippet I doubt you will break it with anything less than an 8 or 9 wt rod unless you have poor material or weak knots.