Not at all. There are different methods of doing this, but they are all quite painful and most fish do not survive the process. Ones that do get shipped out and have all kinds of issues still.
Other fish are also dyed/tattooed. It's basically a trap to get newbies or children to buy unhealthy/tortured fish because they look cute. If they said exactly what was going on, then there would be no business.
It's a good thing you asked on here. Good for you changing your mind.
There are lots and lots of gorgeous fish out there with unnatural-looking colors. If you want a fantastic color, you can easily find a fish that is naturally that way.
55gPLANTED:Rainbows/Loaches/Garras|30gVIV:Crestie|20gL:Leos|10g:Pearl Fighter|5g:Betta|5gChi:Spark Gourami/Badis|5g:ADF|2.5g:Betta|2.5g:Betta|