judging by the darkness of the pics in what i would assume is a brightly-lit tank, i would guess that he's using a really fast shutter speed, so the movement doesn't matter so much. gorgeous fish, and beautiful pics.
50gal planted - yoyo loaches, BNs, odessa barbs, giant danios
33gal planted - praecox rainbows, gold ram, bolivian rams, sparkling gouramis, licorice gouramis, lots of shrimp
2 x 5gal planted - bettas