Painted fish have been around since the 1980s. It is the practice of artificially coloring ornamental fish that are naturally less colorful in hopes to make them more appealing to unsuspecting hobbyists. There are several methods used including injecting the fish over and over with acrylic dye through a hypodermic needle throughout a course of several days or weeks. Another method utilizes a laser that tears away the epidermis, bleaching away the natural pigment and replacing it with a color. No serious aquarist would ever consider buying these fish. They look like they have been drawn on with a crayon and don't come close to matching the beauty of their naturally colored counterparts. People new to the hobby are often the victims of this senseless ploy. They see a gourami with pink lipstick and can't resist buying it for their daughter. They drop the extra cash and end up with fish whose lifespan is severely compromised by their harsh treatment and go home having unknowingly supported painted fish dealers who are physically mutilating live animals.
In the U.S. and in many other countries it is not illegal to sell painted fish. The United States Animal Welfare Act is weak at best when it comes to safeguarding many of our pets. It does not protect animals sold out of pet stores nor does it offer protection to cold blooded animals (reptiles/fish/ect), birds and rodents. Countries like the UK are more proactive about their animal welfare legislation and have significantly stricter laws protecting them. Because of a loophole in their legislation, they too have not been able to stop the import and selling of painted fish in Britain but have made it illegal to perform the practice in that country. Practical Fishkeeping Magazine, a prominent aquarist publication popular in the U.K. and the Untied States, has asked ornamental fish retailers, dealers and transporters to stand up and take a pledge not to sell these fish. Since they started their campaign in 1996 they have gotten 75% of U.K. aquarium retailers to stop selling these fish. Their success is spreading to the U.S. and as more and more hobbyists become aware of the procedure they are choosing to shop at stores that reject the practices by not stocking dyed fish.
Here are some more articles on Painting fish. The first is "How Fish are Dyed" and the second is "Why it is Cruel to Dye".
http://nippyfish.blogspot.com/2006/08/painted-fish-animal-cruelty.html <--- My own first hand experience