There’s a new fish in town—but not everyone’s ready to make room on their plates for it.

Thursday, the U.S. Food and Drug Administration issued its first approval for a genetically engineered animal intended for human consumption. The animal is the AquAdvantage salmon, an Atlantic salmon modified to contain a growth hormone gene from Chinook salmon, turned on by a chunk of DNA from another fish called the ocean pout. These modifications let the AquAdvantage salmon reach adult size far before conventional salmon do.

Already, the FDA’s decision has been challenged by groups like the Center for Food Safety, which issued a statement Thursday that it intends to sue the FDA, and the Canadian organization Ecology Action Centre, which