Where are the fish? The answer -- as you gaze across a river or stream -- is right in front of you.

"I teach students that reading a stream is like reading pages in a book," said Chuck McKinney, a former biology teacher and director of Family Tyes, a Pittsburgh non-profit group that provides teen mentoring through fly fishing. He spoke via cell phone as he led a Family Tyes excursion to the Fisherman's Paradise stretch on Spring Creek in Centre County. "Reading the water is one of the most important aspects of fishing. Once they start to read the book, it's amazing how much success they have."

Trout are masters of biological economics, expending minimal energy to acquire maximum nutritional value while avoiding predators. By studying the surface water, it's possible to understand how that equation is playing out underneath.

Big, deep pools, said McKinney, generally don't hold the best fish. Those less active trout are more likely to respond to passive bait-fishing techniques. When the water warms, they might strike a flashy spinner.

"At the top of the pool," he said, "right where the rapids enter the slower water, the biggest, most aggressive fish will dominate smaller fish and hold a spot directly opposite or within those seams."

"Seams" are the visible divisions -- often marked by a bubble line -- between fast and slower-moving currents. Expending as little energy as possible at the edge of slow water, trout watch a smorgasbord of food passing in the faster current. They dart out for a meal and return.

"At the bottom of big pools, you'll find fish sipping [flies] at the point just before where the current breaks," said McKinney.

Visible structure is important. Where a large rock pokes through the surface, trout hang in the slower water immediately in front of the obstruction. McKinney says to also work the seams to the left and right behind the rock, but bypass the pocket behind the stone unless it's a big boulder or a heavy flow and the backwater is eddying.

"Logs, brush sticking out of the water with a current passing under them is always a great spot for aggressive fish," he said. "Sometimes they won't move very far, if at all, from under the protective cover. You'll sacrifice some flies."

Bait anglers should find the precise upstream vantage point where weighted bait swings through the cover without snagging.

Contact with the bottom also slows the current despite fast-moving riffles on the surface.

"Sometimes there's a current running across, with water moving another direction underneath it," said McKinney. "You can actually see it -- your float isn't going the way you think it should. Use the seam to take the [lure or bait] deep under the current."

Later in the season, read the water for shady spots and tributaries carrying fresh, cool, oxygenated water.

Family Tyes can be reached at 412-884-5866 and familytyes.com.