In approving genetically engineered salmon as safe to eat and safe for the environment, the Food and Drug Administration rejected petitions from environmental and food safety groups asking that companies selling this salmon be required to label it as genetically engineered. Congress should overturn that decision. Consumers deserve to know what they are eating.

The salmon, made by AquaBounty Technologies of Maynard, Mass., has genes inserted that allow it to grow to market size twice as fast as wild salmon. The F.D.A.’s approval permits the engineered salmon to be raised only in land-based hatchery tanks in two facilities — one in Canada, where genes are injected into the eggs of Atlantic salmon, and a facility in Panama, where the fish are grown to market size. Each site has physical barriers to prevent the escape of eggs and fish.

The salmon will be made sterile so that should they escape, they will be unable to breed with other salmon or establish populations in the open sea. Still, such safeguards may not be 100 percent foolproof. The F.D.A. and the Canadian and Panamanian governments will conduct inspections to make sure the safeguards are working. A major concern is what might happen if the technology spreads to larger-scale commercial operations around the world that might have weaker confinement barriers. At least one consumer group has announced plans to sue the F.D.A. to overturn its approval of the engineered salmon.

It will take about two years for these salmon to reach market size, and the Panama facility can produce about 100 tons of fish a year, a tiny amount compared with more than 200,000 tons of Atlantic salmon imported each year. Some leading grocery chains, responding to consumer concerns, have said they won’t sell the genetically engineered salmon.