You guessed it–science! Fluorescent colors are very special. You might have seen fluorescence
before if you have ever seen a blacklight poster or paint illuminated with blacklight. Fluorescent colors seem to glow, because they absorb one color of light and then they emit a different color. This is because of the way the pigment (color) molecules release energy from the light they absorb. When a pigment molecule absorbs light energy, it usually slowly releases the energy as heat. Instead, a fluorescent molecule releases some of the energy from the light it absorbed as new light that has lower energy than the light that was absorbed. Normal pigments just cannot do this—they can only bounce back colors of light that exist already in their environment. That is why fluorescent colors look amazing and a bit unbelievable.
Remember how everything looks blue when you are 60 feet under the sea? Like living blacklight posters, fluorescent fish absorb that blue light, and then they emit red light. Fish that live in deeper, bluer water have even brighter red fluorescence.

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Go to source: https://kids.frontiersin.org/article/10.3389/frym.2018.00059