There are definite signs that fish is fresh. Fresh fish should have a mild scent and moist flesh, and appear freshly cut. Don't purchase fish that has a strong, fishy odor. Whole fish should have bright, bulging eyes and bright red or pink gills. Frozen fish should meet the fresh-smell test and have taut packaging with no evidence of ice or blood. Fresh fish is best used right away. Or, you can store it for up to two days in the coldest part of the refrigerator. Frozen fish will keep in its original wrapping, frozen at 0 degrees or lower, for up to 3 months.