According to a guy in a Facebook group I belong to, this fish was caught in the Missouri River near Omaha, NE, US. I have never seen one like it in my life, not in person or photo or anywhere. What on earth is this fish?! Is it even real? I've not seen it in person, only the photo below, but he says its real.
It looks to me like a species of sculpin, for example, the "short-horned sculpin" Myoxocephalus scorpius.
After some deliberation, and it appears the other very good answer was for some reason removed: the OP fish appears to be a northern sea robin Prionotus carolinus.
This conclusion comes from the aid of user chauxvive, so much thanks for the identification, though his answer is oddly gone. The conclusion is based off of (1) the morphology of the head and face plate, (2) the longer and tapered pectoral fins, (3) the distinguishing long feelers at the sides anterior to the pectoral fin, and (4) the more probable distribution.
I'm glad to see it may be indeed be a sea robin. Please vote for my answer here, if you don't mind, since my other post is gone. The pectoral fins were what I noticed first- robins have such unusual fins!
here's another anatomy of the sea robin. As you can see, it has pectoral fins much closer to this mystery fish than the sculpin.
This is an interesting discussion of the sea robin types and habitat The common sea robin is much larger than the northern and apparently the northern can stand much fresher water. Obviously this is outside of their range (which is along the coast and up brackish rivers of the Eastern US) but mystery fish could be a release. This isn't a popular tank fish, but you can buy and order them online (reference) They are pretty common in new england, apparently.
I looked your strange fish and I think that it is a short horned sculpin because of its spikes.So, don't imagine that it is a sea robin because sea robins live in very deep waters (500 meters depth aproximately).In fact, I think that this sculpin was trapped in the river while it was going to the sea and the fishermen caught it.