thuggin, the reason your verbage in the manual is so vague is becouse the possible use is vague, a sounder obviously works by bouncing a frequency, air in density, or solid refracts it back, thats how it can show hard to soft bottom, the fish are spotted on the sounder by the size of air bladder in it, a 2 lb largemouth is going to appear larger on it than a 4 lb trout simply becouse spiny ray fish such as perch walleye and bass have larger air bladders.... a trout under 8 inches may not show up at all, a sturgeon must be pretty large to be dense enough to show up, but they occasionaly can. Sounders are for finding structure, edge and feed balls... and even the best are not of much more use, now if you wanted to get a side scan sonar you could target individual fish,, but your luck is gonna be pretty low, exept bass fishing, to target individual fish. good luck