The better you get at seeking out and finding fish by sight, the more experience you have with the different actions and reactions of your favored species. As you approach a fish and then work hard to sight cast and catch that fish, you will begin to notice its little changes in body postures and actions that will allow you to “read” the fish — to get to know it so well that you can anticipate its next moves.
Over time, you’ll develop a kind of sixth sense of when you need to back off, be more aggressive or make another cast. You’ll know the course of action you need to take to get the fish to eat the bait whether it wants to or not. That knowledge of a variety of species, along with adept use of a variety of casting, spinning and flyfishing tackle, is a mark of the accomplished angler.
Each fish species displays consistent reactions to threats and excitement, and the better you focus on watching fish closely and then reacting to their postures, the better you’ll get at sight fishing. Sailfish, for instance, will light up and change colors when excited or feeding. When you see a fish light up, you know it’s having a positive reaction to your offering.
Over time, you’ll see that fish strike a lot of different postures that, if read properly, will help clue you in to their mood. Let’s say you’re sight casting to trout in a stream and watching a fish as it reacts to stoneflies landing on the water to lay eggs. As the big flies are swept into the fish’s field of vision, it moves to a point downstream where it can easily intercept a meal.
When you throw your fly upstream of that fish, it moves into position, but when the fly gets close it doesn’t eat. You know the fly has evoked a positive reaction from that fish, but something is keeping it from taking the bug as it gets closer. Likely there is something wrong or weird about the fly, or the fish is seeing the leader. It might mean the fly is tangled, the coloration is a bit off from the natural stoneflies or that the size is wrong. Or it can mean the tippet is too heavy and the fish is seeing it just before it eats. Or the fly is being pulled unnaturally against the current. Watching the posture of the fish over several casts will give you an idea of what is taking place and a simple change will get the fish to bite.
There are times when you’ll see fish change postures from a comfortable position to one on its guard. If that fish hasn’t moved off, it likely detects your presence but isn’t sure where you are. It still won’t eat until it relaxes.
In this instance you want to back off the fish and change the angle of approach. Watch the fish closely from a distance and wait for it to take on a more relaxed posture or a feeding posture before making the longest cast possible. Often, these changes will elicit the strike.