Anglers are often concerned about the diameter of their tippet spooking fish, but are even more concerned about the potential of breaking-off fish as a result of going to light.
I tend to use the lightest tippet possible in order to match the size and strength of the fish size; the targeted fish species; and the resistance of the current. But having said that... I often take the gamble and go really light if the fish are heavily pressured and leader-shy, as I'd rather catch lots of small and medium size fish instead worrying about losing the occasional larger fish and sacrificing my presentation...
In most situations while targeting trout, I'm using 5X for lakes and 7X for rivers, even if there is the hope of encountering the occasional large fish in the mix. I'll use fluorocarbon if I feel the need to increase the breaking strength of my leader without increasing the diameter..
How about the rest of you? How low do you go?!?
