Classification depends on three factors: species (halibut, sole, flounder, Greenland turbot, or other), whether the fillets are skinned and in blocks over 4.5 kg for further processing, and whether the product fits a specifically enumerated line or falls to the NESOI residual. Work through the species identification first, then apply the block-weight and processing-intent tests. A binding ruling from CBP is advisable for non-standard presentations.

Yes, frozen fish fillets of Chinese origin are subject to Section 301 tariffs, which have increased landed costs for product processed in China — including fillets made from fish caught elsewhere and sent to China for processing. Many importers have diversified toward Vietnam, Thailand, and Argentina to reduce Section 301 exposure, though supply quality and species availability vary by alternative origin.