I also think the original use of glowing zebra danios, the detection of water pollution, is a bit unrealistic. How exactly are they going to remove a fish as adaptable and hardy as a zebra from a waterway where it does not belong, without polluting the waterway more trying to poison it?
They aren't used in open waterways, but segments of industrial water systems, where they can't (usually) escape. They're maintained in these systems for their entire life. Fish have been used in this manner for many years, but historically sensitive species are used and the indicator is that they die, rather than a change in color.