Wal-Mart would only care if the 1,600+ people who have signed this petition (including me) vow to not buy ANYTHING from them until they change their practices or stop selling live animals....
For example, changing their practices with regard to care of fish could include ensuring that stores that sell live animals are staffed with people trained to care for animals, stop stocking innapropriate fish like Pacus, and establishing care standards / quality control for the animals department.
If you want to see change, don't buy ANYTHING from Wal-Mart. And let them know why. Poor care of animals is one of many reasons I don't buy from them (e.g. abusive labor practices like cheating employees out of overtime pay, discriminating against military reservists, shifting healthcare costs to the taxpayers, etc.).
Matt