This study assesses the market integration of domestically produced and imported catfish products in the United States. In 2003, the U.S. adopted legislation that established antidumping tariffs for Vietnamese catfish products entering the country. One goal of this analysis is to determine how these tariffs have impacted the relationship between foreign and domestically produced catfish products. Cointegration tests confirm the existence of a long-run price relationship between domestic and imported catfish products, which has persisted despite the legislative change. This finding enables the estimation of vector error correction models to describe this price relationship in the periods before and after import tariffs went into effect. Results from these models suggest that Vietnamese catfish fillet prices do not significantly influence or react to domestic catfish prices. However, the price of catfish fillets imported from countries other than Vietnam has continued to respond to domestic prices, and to influence the prices received by domestic catfish farmers and processors.