Wild-caught seafood has no hormones, antibiotics or drugs. This question usually arises concerning aquacultured or farm-raised seafood products. Unlike beef products, hormones are not used during fish farming. There is, however, a short list of antibiotics that have been approved for use in the United States, by the U.S. Food and Drug Administration (FDA), for aquacultured finfish (e.g. salmon and catfish). Aquacultured shellfish (e.g. oysters) do not have any antibiotics approved for use.
Antibiotics are used for farm-raised finfish for the same reasons that they might be used for beef. These are issues related to infection or illness of the fish. Just like meat or poultry, producers of aquacultured fish must stop administering antibiotics 30-180 days, depending on the antibiotic, prior to sale. This is to assure the antibiotics have been completely expelled by the fish or are far below the level that the FDA have determined to be safe for human consumption.