29 C.F.R. § 784.112
Substantial amounts of nonaquatic products; enforcement policy
As an enforcement policy in applying the principles stated in §§ 784.110 and 784.111, if more than 20 percent of a commodity consists of products other than aquatic products named in section 13(a)(5) or 13(b)(4), the commodity will be deemed to contain a substantial amount of such nonaquatic products.