If I am not flyfishing I'll use them for trout, either trolled when lake fishing or cast into fast water and swung through the edges on decent sized streams. About F4 size, frog and perch are two of my favourites but a gold F5 trolled over shallows just at dark has hooked some nice fish for me! I tend to change out the small trebles for a single hook and usually pinch the barb down.
