In much of the world, genetically engineered crops, including soybeans, corn and canola, are part of the basic diet. Nearly half the fish consumed worldwide are now farm-raised, and aquaculture is an $86 billion business, one that might be about to get bigger. The FDA is reportedly on the verge of approving a genetically engineered salmon that grows faster than the natural kind. It could be the first transgenic animal sold in American markets. What if mutants get into the sea? A so-called “enviropig” might be good for the environment, but is the modification good for the pig or for human consumption? What are the benefits and risks of genetically engineered food? Are there ways of keeping a powerful technology from getting out of control?