Posted 02 August 2010 - 12:29 PM
Here's something you're not going to hear from most fish identification guides -- you can tell most minnows apart by the expression on their faces. Really. The position, orientation, size, and shape of the mouth will separate a very large number of minnows easier then trying to count anal fin rays in the field. Bear in mind that there can be substantial sexual dimorphism -- differences between males and females -- in some groups (Cyprinella comes to mind), but once you get the "gestalt" of minnow heads down, they're not all that difficult.
Next time you're out, spend more time looking at the fish you catch, rather than trying to get as many as you can. Hold them in some clean water in a zip-loc (rather than in your dry hand) and look at the shape of the mouth. Up close. Those little barbels that you can't see in "dry hand pics" stick out, or are at least more visible than when you're shooting pictures from a foot away. Even the little barbels in the groove between the upper lip and the head in fallfish seem to pop out when you can watch the fish open and close its mouth.
Track down a copy of your local fish book (more difficult for you now that Hartel's MA book is out of press) or get a copy of the Peterson guide and learn the other characters, also, but mouth shape won't let you down if you take the time to learn it.
Folks on the Forum like chiming in with their opinions on what a given fish is. Heck, so do I, but that's not going to make you learn your fish. Spend time out looking and observing. Learn your fallfish across a range of sizes (tiny fallfish were my ichthyology prof's favorite way of making exams difficult). When you get a spottail shiner, and look at the head, you're going to be like "WOW, that's no fallfish!"
good luck.