Yes. It depends on the depth and the method and speed of current.
For dry fly fishing you want a knotless tapered leader about 7 feet long, For upstream nymphing in shallow streamy water a short leader, say 4 to 5 feet would be OK and it needn't be tapered.
If the river is clear and deep such as a chalkstream, a 9 foot leader might be best.
Use fluorocarbon for sunk nymphs, it breaks through the surface and sinks quickly.
