The House has moved to prohibit the Food and Drug Administration from approving genetically modified salmon for human consumption.
The FDA is set to decide this year whether to approve the modified fish, which grows twice as fast as the natural variety. An advisory panel said last year that the fish appears to be safe to eat but more studies may be needed before it is served on the nation's dinner tables.
If the salmon is approved, it would be the first time the government allowed such modified animals to be marketed for human consumption.
Alaska Republican Rep. Don Young offered the amendment to a farm spending bill, and it was approved Wednesday by voice vote. Young argued that the modified fish would compete with wild salmon in his state.