rive1404
Aquarium Advice Freak
Surely there are other fish stores in the area that will take free fish. You can always Craigslist them.
Gotta be someone who could take them, just have to think outside the box. Not a good idea to put them in the river, they'll be feeders there too. Might look at large fish places they may have some room, but before you do ask them when their fish shipments come in. That way you can make a better sell on adding just a few more to their stock.
As far as light in the new tank, make sure your new fish like bright light. Might be better to look at the type of light you can get for the tank as different ones will give off a different look. Worth looking into.