LOL they can't swim fast enough to avoid the sonar beam. Just have to practice and like you said, catch a few and note what they looked like on the screen. Sometimes the schools are mixed. One of my friends was in Alabama last week and saw some fish schooling on top. He eased his way over and saw a huge school under the boat. He ended up catching 7 different species of fish out of that school. Perch, LM, Crappie, Catfish(2 types), White Bass and Warmouth. He had never seen anything like that ever!
Mark 1:17 ...I will make you fishers of men