The U.S. Geological Survey has recently observed three Pacific tropical fish species in Florida's waters. In addition to the invasive Lionfish already plaguing Atlantic reefs, the USGS spotted a Yellow Tang, Panther Grouper, and Spotted Scat in a recent survey. More here:
Nah, there yours if you want to kill em, then kill em. Seems stupid when you could go to the LFS and get credit. But its your right. It is however completely unacceptable to dump them into water they aren't native to.
I would add it is unacceptable to reintroduce them to waters they ARE native to, as well. You can't know their provenance, genetic mutation, chemical treatments, or even presence of viral or bacteriological infections which might NOT be native.
Once they leave the waters, it is wisest never to return them...