nope not lying, had a bit of a talk with my lfs about dyed fish, they of course dont sell them but i asked them how did they do it. Told me all about it. Also found on wikipedia
http://en.wikipedia.org/wiki/Painted_fish
A good way to tell is if the fish has fancy letters or I *heart* you it was probably laser dyed, if there are different streaks of color around the body like with the glass tetras, they were probably dyed with a hypodermic syringe. If the whole fish is a different color then they were probably acid dipped dyed.
http://www.youtube.com/watch?v=yH1RkGbziy8, that is probably a laser tattooed fish. Of course it is possible it was also a hypodermic syringe dye.
There is such thing as a food dye, these are more harmless and are more just used to bring out the natural color in the fish. I dont really like the idea of food dye but it doesnt seem that bad (i still dont use it, there normally found in food that say color enhancers like carotene.