I know they don't occur naturally but they are still fish that glow. If you want to know about deep-sea glowing creatures check out the Monterey Bay aquarium. They will be opening a new deep-sea exhibit that will most likely keep some bioluminescent fish.The neon glofish you mention is actually a genetically modified zebra danio, a common freshwater species rather than a real bioluminescent deep sea fish, the latter generally don't survive being brought to the surface. However other bioluminescent fish found in captivity include the pinecone fish and cardinal fish of the Rhabdamia genus