This beautifully striped fish was photographed at the Living Planet aquarium in Sandy, Utah. I would like to say that my extensive knowledge of tropical saltwater marine life allowed me to correctly identify this species, but that would be an absolute lie. It took a commenter on Flickr to inform me that this is a Banggai Cardinalfish. And now I know.
Canon 30D, Canon 24-105 f/4L IS lens – 1/30 second, f/4, ISO 400