Lots of people have to do thing they don't want to do at work, that is why it is called work and not play....inform people of the facts but don't tell them anything about how you feel, hurt the business and you'll find yourself out of a job FAST...
sad fact is people sell what sells...and if you try to be a hero you'll end up a zero.
BTW...what happens to all these dyed fish if people don't buy them ?? I guess we never thought of that fate yet...
I am no fan of dyed fish but would rather see them ina tank then crowed together in some fish store...so if that is what the customers want then sadly you are forced to sell them, don't blame the store to much...just explain to people how they got that way, without trying to discourage them and all will be fine..