You could be right about this one as well. :)
So, most likely it is a Black Crappie.
One of the things I was doing when I left the laboratory at CSU, was working on a paper regarding the crappie presence in the Upper Colorado River Basin.
However, because I lacked conclusive evidence (genetic), the paper will not be useful for identification.
One of the things I learned during my literature search is that when black and white crappie are both present in the same waterbody, hybridization can, and will mostly likely, occur. The amount of hybridization is dependent on the size of the body of water, the habitat available, and the density of both species.
An interesting topic is the genetics of the crappie. Apparently Black Crappie contain the dominant traits!! Some of the coloration characteristics that were once thought to be strictly Black Crappie, such as the "black nosed" crappie, can be present on some hybrids, but not present on White Crappie.
Another topic is the spine count. Eight and greater spines seem to be associated with Black Crappie and six and less with White Crappie. Seven spines appears to be both pure and hybrid Black Crappie.
Pigmentation can be somewhat of an indicator, but can be very subtle with hybrids and pure Black Crappie.
Dorsal fin length base compared to the length of the nape (posterior of the eye to the origin of the dorsal fin) appears to be helpful. White Crappie have a short dorsal fin and will usually fit within the nape around 1.3x. Pure Black Crappie have a long dorsal fin base and it will be greater than the nape. However (again, another caveat), crappie with a fin to nape length around 1:1, or same, could very well be hybrid, even though they also display either crappie species characteristics.
It truly was fascinating doing all the research and reading. However, I believe that some of it needs to be taken with a grain of salt. Looking at the general populations in the vicinity and the densities of the crappie. Most of the crappie I catch in Colorado are Black Crappie. However, Colorado does hold a few White Crappie. White Crappie do not hold a majority and since there are a few, the chances of them hybridizing with Black Crappie is possible.
Thanks for letting me rant. Beautiful fish!