Philip Shaddock was the guy who created them. Here's a snippet of what he has said about them on Guppy Designer.
"I have been creating a transparent guppy by crossing an albino blau X glass belly guppy. The homozygous albino blau fails in the production of black, red and yellow color. The glass belly guppy fails in the production of iridophores in most of the body, with the exception of the fins. The resulting guppy has visible internal organs and you can see the blood. I have to take a picture.
The new strain appears to be more delicate than normal guppies. I have a female that was very weak, and I regularly change the water. The young females have transparent bellies so you can see whether they are carrying eggs or young. So far all I have seen are eggs. So the single male must be infertile."
"you see the organs and the blood, especially around the gills where oxygen exchange is occuring. You clearly see the blood vessel traveling along the spine to the back of the body and the heart and brain. You can see food passing through their gut. And when they have a bacterial infection...like that weak female, you see the inflammation in the body. But the most useful aspect is that you can see the eggs and developing fry. That's why I think the two females I have have not been fertilized by the male. The eggs have not developed. Normally with glass belly pandas I can see the fry curled up and their black eyes. So it is easy to for me to set up a female who is about to drop. "
"Yes, the strain has proven to be more hardy and fertile than I expected. I guess I was just prejudiced to believe they would be fragile. The female shown is actually close to giving birth. But because the eyes have no black color, it is difficult to see that the fry are full grown. My first batch of fry are a month old and they eat like hogs.
They are going to be useful in my genetics studies because the major classes of color cells are affected. Interesting enough there appears to be some yellow color cells at the base of the peduncle and in the head. They should not be there. "