The Food and Drug Administration's "frankenfish" powers are being challenged in court.
A collection of environmental, consumer and fishing groups is suing the agency over its authority to approve genetically modified salmon.
The lawsuit announced Thursday takes aim at the FDA's decision last year to approve the first-ever genetically engineered salmon that can be grown quickly.
The coalition of groups argues in its lawsuit that the agency never had the power to approve and regulate genetically modified animals as "animal drugs" under federal law.
"Those provisions were meant to ensure the safety of veterinary drugs administered to treat disease in livestock and were not intended to address entirely new [genetically engineered] animals that can pass along their altered genes to the next generation," said environmental law group Earthjustice, which is part of the lawsuit.
The FDA approved salmon from AquaBounty with several restrictions. AquaBounty can grow the salmon, which grow quicker than natural fish, only in pens to prevent their escape into the wild. The fish can be grown only in two land locations in Canada and Panama, the agency said.
The FDA added that environmental studies have found the salmon is safe to eat.
Earthjustice said that when the salmon escape or are accidentally released, they could wreak havoc on ecosystems by crossbreeding with native fish.
"This case is about protecting our fisheries and ocean ecosystems from the foreseeable harms of the first-ever [genetically engineered] fish, harms FDA refused to even consider, let alone prevent," said George Kimbrell, senior attorney for the Center for Food Safety, another group in the lawsuit.
The FDA said that it does not comment on pending litigation.
The agency decision not only upset environmental and food safety groups but also some lawmakers.
Sen. Lisa Murkowski, R-Ala., termed the salmon "frankenfish" and has slammed the agency's decision. Murkowski comes from a state with a robust fishing industry.
The senator has pushed for mandatory labeling of all genetically modified salmon so consumers know what they are eating.