A while ago, scientists at the National University of Singapore created transgenic, fluorescent zebra fish by injecting red, green, and orange fluorescence genes from a jellyfish into the fish eggs. They did this so the fish could help detect environmental pollutants.
Now, you can actually have them for pets! They are marketed under the name GloFish, and look very cool under a black light. Link - Thanks moniA!
Previously on Neatorama: Fluorescent pig, rabbit, butterfly, and frog
Sorry so long but for ppl having problems with getting the fish to glow try buying a black light.