Whole Tilapia is generally good for up to two days if it's refrigerated immediately. However, it's a good idea to avoid placing the fish in the front of the fridge, as it will lose its freshness after eight hours. Similarly, if you're planning on freezing tilapia, make sure to refrigerate it after thawing it. Keeping it in the refrigerator can also prevent it from developing an unpleasant odor.