Fishery products (i.e., seafood), including wild catch, aquaculture, and processed fish products, are one of the most highly traded commodities in the world today, and more than half of this commodity originates in developing countries. The EU is the largest market for imported seafood, followed by the United States and Japan. Roughly 20 years ago, about 60 percent of the seafood consumed in the United States was imported. As of April 2016, over 90 percent of the seafood consumed in the United States was imported, about half of which was produced from aquaculture operations, also known as fish farms. In 2015, China was the overall leading exporter of seafood to the United States, India was the leading exporter of shrimp, and Vietnam was the leading exporter of catfish. Figure 1 shows the proportion of U.S. imports from the five countries exporting the most seafood to the United States in 2015. The “others” category represents 137 countries that also exported seafood to the United States in 2015. Figure 2 shows the countries that in 2015 were the major exporters of shrimp, salmon, tilapia, and catfish to the United States. As with seafood more generally, the volume of imported catfish has been increasing in recent years. In 2005, the United States imported over 30 million pounds of catfish. In 2010, the United States imported about 137 million pounds; the major catfish exporters were Vietnam, with 79 percent, and China, with 13 percent. By 2015, total catfish imports were almost 250 million pounds, with Vietnam alone accounting for over 95 percent of all such imports. Domestically, catfish production is concentrated in Alabama, Arkansas, Louisiana, and Mississippi. In general, according to USDA, domestic catfish production has trended downward in recent years, but data in this regard are incomplete. For example, data reported by USDA’s National Agricultural Statistics Service showed a general decline in domestic catfish production from 2006 through 2012, including a 36 percent decline from 2010 to 2012, from about 472 million pounds in 2010 to about 300 million pounds in 2012. But this agency did not collect and report similar data for the period 2013 through 2016. Before 2002, various fish in the order Siluriformes were commonly labeled and sold as “catfish.” However, in 2002 Congress amended FFDCA to allow only fish from the family Ictaluridae (in the order Siluriformes) to use the name catfish in labeling. All other fish, such as those from the Pangasiidae family (in the order Siluriformes) that had previously been labeled as catfish had to have other names on labels, such as basa, swai, or tra. However, as discussed, the 2014 Farm Bill made all fish in the order Siluriformes subject to FSIS inspection upon the issuance of final regulations. For purposes of this report, we refer to all fish potentially subject to FSIS regulations as “catfish,” including fish in the family Ictaluridae, which are primarily of domestic origin, and Pangasiidae, which come primarily from Vietnam. In the United States, new animal drugs (veterinary drugs) used in animals that are used for food, including seafood, generally must be approved by FDA. According to FDA officials, the process for obtaining a new animal drug approval, including drugs used in aquaculture, originates with an entity or individual (sponsor) submitting an application for review. FDA may approve a drug for, among other things, certain disease conditions in specific species (e.g., catfish). When FDA approves a drug, it may establish a tolerance for the safe use of the drug. If residues of the approved drug are detected in a food product above the tolerance, the product is unsafe and therefore adulterated under FFDCA. Once residues are confirmed above a tolerance, which can vary by species and drug, FDA may take regulatory action. In addition, if any residue of a drug unapproved by FDA is detected, the food product is likewise unsafe and adulterated under FFDCA. In general, drugs used in aquaculture may include anesthetics, antibiotics, disinfectants, hormones, parasiticides, and germicidal agents. Table 1 lists the drugs that FDA has approved for aquaculture use in the United States as of February 2017. For testing drug residues, FDA has established three types of maximum residue levels (MRL) for seafood intended for consumption in the United States. FDA applies two of these levels—the “tolerance” and “regulatory” levels—to domestic and imported seafood. The third, “import tolerance” applies only to imported seafood. FDA regards the presence of drug residues above any of these levels to be potentially harmful to human health and may consider taking regulatory action, such as refusing a product’s entry into the United States if it contains drug residues above such levels. More specifically, the three levels are as follows: Tolerance: For drugs FDA has approved for use in aquaculture, the approval is often for specific species, disease conditions, and a maximum drug residue tolerance. A food product with a residue above the tolerance established for the drug in that food is adulterated under FFDCA. Tolerances for approved drugs are established in regulation and codified in the U.S. Code of Federal Regulations. FDA applies established tolerances for FDA approved drugs to imported and domestic seafood. Regulatory level: For certain unapproved drugs, FDA has also established maximum drug residue levels that for purposes of this report, we refer to as regulatory levels. In general, these levels correspond to the limits of detection achievable by the testing methods and equipment used by FDA laboratories. FDA does not generally publicly disclose regulatory levels for residues of unapproved drugs. According to agency officials, FDA is concerned that disclosing its regulatory levels for unapproved drugs may encourage some foreign fish farmers to use these drugs if they believe that they can do so in a manner that would result in residue levels below FDA’s regulatory levels. Import tolerance: For certain drugs that may be used by foreign fish farmers, FDA has established import tolerances. These drugs are not approved for use by domestic fish farmers. FDA has established import tolerances for three drugs that can be used in other countries on seafood, but none of them are for catfish. The EU, which is the largest importer of seafood worldwide, takes a wide- ranging review of the food safety systems of foreign countries that want to export their seafood products to it. Specifically, the EU requires that other countries seeking to export seafood to it demonstrate that their seafood safety systems meet its or equivalent requirements or comply with specific requirements established in an agreement between the EU and the exporting country. According to EU regulations, for other countries to demonstrate that their seafood safety systems meet EU or equivalent requirements, they must provide information on their food safety systems, including relevant laws, regulatory enforcement powers, and the laboratories that test seafood products. According to EU officials, once they determine that a country has an equivalent food safety system for a particular food product, the government of that country is then responsible for meeting the EU’s safety requirements. Moreover, that government becomes the single point of contact to address any identified problems, such as seafood products with drug residues above the EU’s accepted MRLs, and is expected to take regulatory actions across that country’s supply chain, from farm to processing facility, as necessary. The EU generally conducts an on-site audit of a country’s food safety system governing the product that country seeks to export to the EU. The audit focuses on the ability of the competent government authority responsible for food safety to carry out its tasks and provide the necessary guarantees for the safety of food to be exported to the EU. The EU’s on-site audits include visiting fish farms and processing facilities as well as reviewing the capabilities and quality of the country’s food testing laboratories. In addition, to ensure continuous compliance with EU requirements, the EU periodically conducts follow-up audits of a country’s food safety system for specific food products, such as seafood. Countries that export food to the EU also are required to implement national residue monitoring plans, which include sampling and testing of food products for residues of specific drugs of concern to the EU. The EU must approve a country’s residue monitoring plan as a prerequisite for export of food of animal origin, such as seafood, from that country to the EU. Countries exporting food to the EU must submit their residue monitoring plans to the EU for approval each year. The EU can prohibit a country from exporting seafood to the EU if drugs of concern to the EU are not included in the country’s national residue monitoring plan or the country does not otherwise fully implement its plan. To help ensure the safety of imported seafood from unsafe drug residues, FDA generally depends on the actions of foreign processors and U.S. importers. Specifically, FDA requires processors and importers to follow its Hazard Analysis and Critical Control Point (HACCP) regulations to identify hazards and the critical control points where the hazards, such as pathogen contamination, are likely to occur and to take corrective action. FDA also performs a limited number of (1) inspections of processors and importers each year to ensure HACCP compliance, and (2) samples and tests of imported seafood for contaminants, including unsafe drug residues. However, FDA has not entered into agreements with other countries requiring that they test seafood exported to the United States for the specific drugs the agency tests for—drugs of concern to FDA. Since 1997, FDA has used HACCP as its main safety oversight tool for imported seafood. Under HACCP requirements, seafood processing firms, including firms that manufacture, pack, or label, are responsible for conducting a hazard analysis and for developing and implementing HACCP plans whenever an analysis shows that one or more hazards, such as pathogens or chemicals, are reasonably likely to occur.