0303.83.00.00 - Toothfish (Dissostichus spp.)

HTS Code 0303.83.00.00 specifically covers frozen toothfish, scientifically classified under the genus *Dissostichus*. This category encompasses both Patagonian toothfish (*Dissostichus eleginoides*) and Antarctic toothfish (*Dissostichus mawsoni*), often marketed as "Chilean Sea Bass" due to their similar appearance and culinary use, despite the common name not being a strict taxonomic identifier. These are large, deep-water predatory fish known for their rich, white flesh.

This classification is distinct from its siblings which cover other specific types of frozen fish. For instance, 0303.81.00 is for dogfish and sharks, which are cartilaginous fish with a different skeletal structure and market profile. Similarly, 0303.82.00.00 pertains to rays and skates, which are flat cartilaginous fish. 0303.84.00.00 is for Sea Bass, a different family of bony fish. The broad residual category, 0303.89.00, is for any other frozen fish not otherwise specified in subheadings 0303.81 through 0303.84.

As a leaf node, HTS Code 0303.83.00.00 has no further subdivisions. Therefore, classification into this code relies on the accurate identification of the fish as belonging to the *Dissostichus* genus and being presented in frozen form, excluding fillets or other processed meat of heading 0304. Practical classification will typically involve verifying species identification through available documentation, labeling, and potentially physical characteristics if visual inspection is possible.