Nice pics
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I posted in one of your threads on MFK awhile back (my name over there is ShadowBass), and I've noticed after reading about the pricklies they'll turn a dark brown or green with little to no pattern when showing breeding coloration (this also goes for some other species). So keep watching the dark green one to see if he ever changes colors and we might be able to identify him. He may just be another prickly sculpin, but in breeding color.
I'm not sure whether you're keeping him with other prickly sculpin, but if not you may want to move him/her and see if you can get any fry.