1504 - Fats and oils and their fractions, of fish or marine mammals, whether or not refined, but not chemically modified:

HTS Code 1504 encompasses a specific group of fats and oils derived exclusively from aquatic sources. This category includes those originating from fish or marine mammals. The classification applies whether these substances are in their crude form or have undergone refining processes, provided they have not been chemically modified. This ensures a clear distinction for trade purposes, focusing on the natural state of these animal-derived lipids.

This category is situated within Chapter 15, which broadly covers animal and vegetable fats and oils. However, 1504 is distinctly separated from other chapters or sibling categories that might deal with terrestrial animal fats (e.g., lard, tallow) or vegetable oils. Its focus on marine life distinguishes it from broader categories of animal fats and oils by specifying the biological origin of the raw materials.

Within HTS 1504, further subdivisions are made based on the specific source animal. The subcategories differentiate between oils derived from fish livers (1504.10), fats and oils from other parts of fish (1504.20), and fats and oils exclusively from marine mammals (1504.30). This granular classification allows for precise import and export control and tariff application based on the unique properties and common uses associated with these different marine-derived fat and oil products.