i will adress the nastier responses first- A) I would only sell to people who a re responsible (I realize that this is a subjective distinction) B) this would not harm the fish in any way
now, These fish would be genetically altered to produce either luciferin and luciferase, which are responsible for bioluminescence, or GFP. This color would not fade, as teh fish's genes would be producing these proteins. It is possible that the fish will be able to self regulate when they glow with GFP, and almost definitely with blue bioluminescence. However, the luminescence will definitely show. While I would like to make these fish breedable, I will most likely not due to the risks of GMOs interbreeding with natural populations. It would be something akin to the modified danio rerio selling under the name 'glofish'. These fish would be sellable in the US (indeed, most likely only in the US, as that is where I am located). Also, the nature of the genetic replacement will either cause near to the entire fish to glow, or else will glow along natural color pattern lines in the fish, depending on the techniques used.
finally, a message to all, but especially any potential or past flamers:
You hate dyed fish, I hate dyed fish, we all hate dyed fish. I originally thought of this idea to substitute for dyed fish, as suggested in one of the posts. So ask yourselves- would you rather preventa possible solution to this practice, or would you rather just continue to be angry at those who do it?