The Food and Drug Administration on Thursday approved genetically modified salmon, the first such altered animal for human consumption in the United States.

The Obama administration has stalled in approving the fast-growing salmon for more than five years amid consumer concerns about eating genetically modified foods. But the agency said the fish is safe to eat.

By altering genetic materials, scientists have proposed - and in some cases, actually created - animals that would be bred to be disease-free, cleaner in their environments or grow more efficiently.

Opponents of the technology have taken advantage of increasing consumer concern about genetically modified foods and have urged several major retailers not to sell it.

Some retailers have pledged not to sell the salmon, which has an added gene from the Pacific Chinook salmon that enables the fish to produce more growth hormone and grow faster.

There is no evidence that the foods would be unsafe, but for some, it's an ethical issue.

The FDA said in 2010 that the modified salmon appears to be safe to eat, and said in 2012 that the salmon was unlikely to harm the environment.