Given the form of the ripples, I suspect this juvenile Snowy Egret (Egretta thula) had its eyes on a crab rather than a fish.
Its yellow feet, sometimes called ‘yellow slippers,’ make these birds unmistakable as adults, but it can be easy to confuse young Snowy Egrets with juvenile Little Blue Herons. In this case, the lime green leg color, the black bands on the front of the legs, and the crouched foraging posture helped to confirm its identity.
Although I watched and waited for nearly ten minutes, the strike I anticipated never came: the prey continued to swim, and the bird continued to watch. If patience be a virtue, this is a very virtuous bird.