from the September 15, 2013 Newsletter issued from the Frio Canyon Nature Education Center in the valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau; elevation ~1750m (~5750 ft); N29.62°, W99.86°; USA
PLAINS LONGER SUNFISH
As the drought continues, small, isolated pools of shallow water remaining in the gravel and cobblestone bed of the Dry Frio River grow smaller and sometimes disappear. You never find dead fish in the bottom of dried-up pools, though. Raccoons, herons and the like capture the fish days before the water disappears.

Some of the Dry Frio's pools still hold goodly numbers of fish, mostly Largemouth Bass and the species shown below:

That fish is about four inches long (10cm). When I first saw this kind of fish I figured they were Bluegills, halfway remembering that this is what the "sunfish" looked like when I was farmboy fishing in the pond back in Kentucky. They also had dark spots at the back ends of their gills. However, other species also have dark spots on the gills and people use other names for fish more or less looking like what's in our picture -- crappie, perch, sunfish, pumpkinseed, bream, coppernose and more -- so the time has come to sort all these names out, and figure out what a sunfish really is. Being a rank amateur at ichthyology, it takes time with me.

You may be interested in PremierAngler.Com's page on 13 different sunfish species.

In figuring out our species, I noted that the front end of a White Crappie's "dorsal fin" -- the big fin on top -- begins with five or six sawtooth-like spines before the fin enlarges and the spines no longer project above one another. Fortunately I had a picture -- a blurry one that otherwise I'd delete -- showing the number of sawtooth spines on our fish, and that displays a dorsal fin beginning with nine, ten or so spines, not five or six, so our fish isn't a White Crappie. The blurry picture appears below:

Looking at lists of fish known to occur in the Dry Frio River and paying attention to spine numbers, I figure that the fish in our pictures really are Bluegills, LEPOMIS MACROCHIRUS*.

Thing is, among fish, species coloration can change drastically according to age, sex, breeding season and environmental influences. However, the basic structure doesn't change no matter what color the fish is, and such details as how many spines occur in a particular fin are as important in fish identification as number of stamens can be in plant ID.