Is your tank glass or acrylic? If it's acrylic then just remove half the water, put the tank in a shallow box of some sort so it won't tip over, and move the whole thing (with the fish in it) since you're not going far. I've done this plenty of times with my 5 gallon acrylic tanks during power outages when I moved them to my sisters house until our power came back on. Then when you get to the new house just plug it back in and add come new water. Easy as pie.