That's trippy, if anyone knows what causes this, I'm super curious. If someone injected these little guy's eyes, then I hope those people can never reproduce.
I wager GFP gene splicing from jellyfish...Glow Flourocent Protein. its offered in "glow fish" like danios, tetras and barbs as a LFS staple...Also very popular in the Axolotl hobby. Coolest ive seen so far was in an article using the protein in genes of Florida/spotted gar . Its not dyed or injected into the eyes as some stated. I believe its introduced in the egg stage of fish then when that generation breeds their offspring retain the gene.