Playing a fish in moving water introduces some special challenges. When
it's a small fish, you can just strip in line, as if you were retrieving
line. But when you get a frisky fish in fast water, that's another story.
It's always best to get downstream of a fish so that it has to fight
against the current. Also the hook will often pull out of a fish when it
fights directly downstream of you. If you hook a big fish in fast water,
the best thing to do, if you can, is to move to shore or shallow water
where you can move quickly to get downstream of the fish and then put
pressure on it so that the fish darts upstream. A fish will always move in
the opposite direction from which pressure is applied.
But you can also turn a fish's head to steer it where you want it to go,
because a fish can only swim in the direction its head is pointing. Once
you get a fish close to you, use this idea to lead the fish to exactly
where you want it to go.
To net a fish, lead it over the top of the net and then lift the net from
under the fish. Never swipe at a fish with a net. That will usually make it
bolt, and you can break a fine tippet by swiping at a fish with a net.