They are not bioluminescent—they will not glow in a completely dark room without a light source.
The fluorescent protein genes are integrated into their DNA, ensuring the color is passed on from generation to generation. 2. Varieties and Colors
GloFish are a popular brand of genetically engineered freshwater aquarium fish known for their vibrant, fluorescent colors. They are not injected with dye; rather, they inherit their glow from parents modified with genes from marine organisms like jellyfish and coral. 1.