NO!!! freezing WILL NOT WORK FOR TROPICAL FISH!! only for cold water fish! Tropical fish suffer the same way humans do, slowly and painfully, with ice crystals forming in their blood stream, and freezing gills so they suffocate for a long painful time. Cold water fish in the freezer WILL go dormate and fall asleep essentially. Although you should start with the fridge, then freezer once they are really lethargic, because it takes time to go into a "coma" after that, just keep them in there for hours until it's a block of ice to make sure your fish is really dead.