Very rarely in life do we really come up with an idea that is truly our own. The idea that we can use public data that no one knows about and create a lure selection tailor made specifically for the exact spot that we fish is the closest I've come I guess. Just about every stream in the United States big enough to be of interest to fishermen has been sampled by the EPA. Large creeks and all rivers have been surveyed at multiple points along their length. I know here in Ohio our rivers probably average having been electrofished by the EPA at roughly a four mile interval along their length. What this means is that you can get a snapshot of what lives in not just your river but what lives in the section of river you fish in. And trust me I've been looking at these things for a while now and they can vary wildly, even in the same watershed. The river might have ten darter species in a headwater section with the majority of those being of one or two species in particular while in another section there are literaly thousands of central stonerollers and then in the lower river there may be more shad than anything else. And sections just a few miles apart can vary as well. And quite often the species makeup in the tribs is nothing like that in the main river. For instance here are a couple examples.
So lets say you have looked up your favorite stream and have found a couple fish you want to base your lure selection on, what's the next step? Well then you go to one of a couple of really cool websites. You google either "WI fish ID" or "Species Guide Index ODNR" or preferably both. I won't give you the exact web addresses because as soon as I do they will surely change but if you google those phrases the appropriate site will be the first thing that pops up. I know one site has already changed a couple times even though it still has the same information. One site is managed by the University of Wisconsin and the other by the Ohio Department of Natural Resources and they both give you roughly the same information but in different key ways. For example if you look up spotfin shiner on the WI fish ID site it will give you multiple photos of a spotfin from different angles and explain the differences in appearance in adults and subadults and breeding fish. The ODNR site has one photo that is not nearly as nice but it gives you more detailed information including the most important thing of all, how the fish uses the habitat. If your baitfish is a riffle species instead of a pool species or vice versa it is very important to know that. Armed with the information from both sites you can choose lures that closely resemble the most abundant forage in your stream AND fish each of these lures where and how they will appear naturally. Our spotfin shiner is a dead ringer for a slightly larger flatter lure like a usb swimbait fished higher in the water column on a slightly weighted swmbait hook while something like a channel darter would be better imitated by a rounder lure like a ribeye or grub fished on the bottom on a lead jighead. So not only can you fish lures that look like the predominate baitfish in your river section you can fish different lures depending on whether or not you are fishing wood or rock or riffle or pool. With a bit of research you can have the absolute best lure selection for your particular stream that has ever existed! Yeah, the whole concept gets me a little excited. And this can even be applied to favorite lures you already use. Like to use a topwater? Then use topwaters that mimic the chub and shiner species in your streams that spend the majority of their time high in the water column picking things off the surface. Like minnow plugs? There are a million different lure profiles and color combinations available now that let you fish them anywhere in the water column and imitate nearly anything. And the king of baitfish imitating lures are soft plastics with every size shape and color combination you can think of. For example just in the Vic Coomer line you can fish flatter profile curly shads in different sizes and colors to imitate dozens of different minnows, shad, chubs and shiners, There are USB swimbaits that perfectly imitate different shiner species and grubs, curly swims, and ribeyes that will match every other round bodied darter and minnow species in the river.
I think both the WI Fish ID site and the ODNR site pretty much cover the complete variety of baitfish you will find in any of the streams that hold smallmouth bass in the eastern United States. The problem in some states is getting your hands on the electrofishing data. It is out there but sometimes it takes real detective work to find it. The way each state stores and presents their data is up to that states individual EPA. For example here in Ohio it is extremely easy to find. You google "water quality and biological reports index" and you will get a page that lists every report for every stream. Just scroll down and find the one you want and click on it. The true gold is not normally in the report itself but in the appendices to each report there is where typically is listed the electroshock data for each specific sampling location. Some other states make it virtually impossible to find their data without knowing exactly where to look. Probably your best bet there is to google your states individual EPA and find someone there you can call or email. Another option if you are stuck is to google "wadeable streams assessment epa" and download the pdf. It lists who is in charge of each region of the United States for the EPA on the federal level and their contact information. This also makes for some heavily weighted namedropping with your state EPA. "Well, Harvey Brown that heads the Eastern Highlands Region said I should contact YOU and YOU would help me."
If this all sounds like too much trouble (it's worth it), there are a few general rules you can go by that will still improve your lure selection for your particular stream. Most pool species are flatter in profile and lighter in color leaning heavily towards the shiney and silvery hues. Pool species are also often much higher in the water column on average than riffle species. Riffle species are generally a bit smaller and more rounded in profile. They tend to be darker in color but often have brighter wild colors mixed in. Google darters, madtoms, and sculpins to get an idea of their general appearance. Riffle species usually stay tight to the bottom to avoid the heavy current of the riffle. Riffles are also full of dark or brownish arthropods like hellgrammites, dragonfly larvae and crayfish that smallmouth feed on as well.
"The Stream Fishes of OHio Field Guide" is available online as a pdf that you scroll down and get a quick overview of the various stream fishes, their habits and their appearance and is very useful for getting a general feel for what small stream fish look and act like. If you, like me, live and fish in Ohio, a great book to own is "A guide to Ohio Streams" put out by the Ohio Chapter of the American Fisheries Society. It's full of information on how the food chain in the river works as well as a wealth of information on every watershed in the state as well.