There are all sorts of weird things out there swimming amongst our toes. On a recent trip to SoWal (I posted about it a while back), I landed a "grand slam" of motley species on a fly-rod, including a leatherjack, a needlefish and a lizardfish.
Leatherjacks are in the jack family, naturally, but these little guys have two small spines near the anal fin that are poison-filled needles. I learned about these fish while fishing on the Fort Walton pier years ago -- a fellow tourist standing next to me caught one, grabbed the fish to de-hook it, then yelped in pain. A few minutes later, his hand looked like an angry version of the Hamburger Helper mascot. A very caring local stood nearby and observed the whole deal, but only half-heartedly muttered, "You grab 'em wrong and they'll puff you up a bit." Lesson learned.
Needlefish seem to be everywhere. You've probably encountered them on most trips. During the early fall, a quickly retrieved spoon or glass-minnow fly will solicit mulitiple follows by these snake-like fish. Typically, inshore, they're not very big -- and more of a pest than anything. They look like little, skinny, blue/green versions of freshwater gar and love to roam the "still" water of a slack tide. Lots of little sharp teeth fill their long narrow snouts, so you have to be careful in handling them. They're not much sport, but apparently make decent bait. Their cousins, the Houndfish, can get quite large, however. I've only seen pictures (mostly from southern Florida) of these guys.
While there could be a snakehead or two out there somewhere (they seem to be cropping up everywhere these days), I believe most -- if not all -- of the true snakeheads are freshwater fish. You may have hooked a lizardfish, which is one of the more heinous critters roaming the beaches. This
link will introduce you to this vile denizen of the ... well, shallows. Underwater, they're pretty colorful (but still heinous). Out of water, they lose a lot of their iridescence ... but retain their heinousity (may have just invented a word there).
That could have been what you've been catching, but really, there's no telling. Snakehead sounds cooler anyway, so I'd probably go with that.
Hope this helps.