The US tariff schedule separates sea smelts from freshwater smelts at the 10-digit level. Sea smelts (e.g., surf smelt, night smelt) are anadromous or marine species, while freshwater smelts include species such as rainbow smelt (Osmerus mordax) that spend their life cycle primarily in freshwater. The species identification on the commercial invoice determines which line applies.

Frozen fish entering for human consumption must comply with FDA labeling regulations, including the requirement to bear the market name accepted by FDA's Seafood List. 'Smelt' is an accepted market name for several Osmeridae species, but importers should verify the specific species against FDA's current acceptable market name guidance to avoid misbranding issues.