at first, I was thinking Spotted or Florida, but then I scrolled down to 2nd picture, and definitely Alligator Gar - the mouth is a dead give-away - always has a hooked overbite on the top jaw.
What state/region are you located? This fish will likely top 5-6 feet, but is rumored to grow even 12-14'. They aren't necessarily fast growers, but it will need VERY large tank, likely will need to be custom built, or a pond but I have seen a member w/ a really cool swimming pool for his fish in the basement.....even then, 10' diameter and 3' deep is still pushing it. That fish will eventually grow MASSIVE and weigh a few hundred pounds.