Fentanyl Eradication and Narcotics Deterrence Off Fentanyl Act or the FEND Off Fentanyl Act This bill requires or authorizes various actions, including sanctions, targeting foreign persons (individuals and entities) engaged in trafficking of fentanyl and other illicit opioids. This bill requires that the sanctions specified in Executive Order 14059 (relating to sanctions on foreign persons involved in the global illicit drug trade), as well as any amendments to or directives issued pursuant to that executive order before the date of the enactment of this bill, shall remain in effect. The bill also requires the President to impose property-blocking sanctions on any foreign person knowingly involved in (1) significant trafficking of fentanyl, fentanyl precursors, or other related opioids by a transnational criminal organization; or (2) significant activities of a transnational criminal organization relating to the trafficking of fentanyl, fentanyl precursors, or other related opioids. The Department of the Treasury is authorized to take certain actions relating to classes of transactions that (1) involve a non-U.S. jurisdiction, and (2) are of primary money laundering concern in connection with illicit opioid trafficking. For such transaction classes, Treasury may require domestic financial institutions to (1) take certain special measures, (2) prohibit certain transmittals of funds, or (3) impose conditions on transmittals of funds. Treasury's Financial Crimes Enforcement Network must issue guidance to U.S. financial institutions for filing reports of suspicious transactions related to suspected fentanyl trafficking by transnational criminal organizations.