I'm guessing that it's just a dark male spawning redear. I've seen a lot of shellcrackers that look like that when they're on the beds in the spring.
Travis's fish from the thread he linked is what the hybrids look like. Note that the vertical bars on Travis's fish aren't as distinct - the markings on the side are more "muddled."
In certain places you can buy the hybrids for pond stocking.
bd
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