How do you remove rotten fish odor from garage floor in winter?

Cover with baking soda for day or so, sweep up. Cover with coffee grounds for a day or so, sweep up. Crumple up newspaper lay on ground, change daily for 2 or three days . Then mist with vinegar and if its not frozen crumple more newspaper to set on top of it. You can also try scrubbing with a mixture of hydrogen peroxide, baking soda, and a dash of dish soap. Or buy Concrete Odor Remover or Dead Animal / Rodent Odor Remover from Petco. If if it still smells after that move out!