The ruby puppy glows red because the scientists inserted a gene from a type of sea anemone that produces red fluorescence.
Also, Sheldon’s “fish night lights” have been a thing for awhile. Zebra fish are one of the scientific go-to’s for test subjects and have been made able to glow for awhile now. One company makes and sells the glowing fish as pets. They claim that their original intention was to have the fish act to detect pollutants in the water, but I’m thinking they were thinking more along the lines of “this is gonna be sweet” and “cha-ching!”.