Washington ? Consumer advocates, environmentalists and other opponents of genetically engineered salmon told the Food and Drug Administration Tuesday that it would be irresponsible not to label the fish in the grocery store if it is approved for human consumption.

Consumers want to know what they are eating, they said.

The agency heard from all sides this week as they held hearings to review the science of the fish that grows twice as fast as the conventional variety and to hear public comment on whether the fish should be labeled. According to federal guidelines, the fish would not be labeled as genetically modified if the agency decides it has the same material makeup as conventional salmon.

The FDA has not yet decided whether the fish can be marketed or labeled, and it could be months before they do.

Consumer advocates say it is the public’s right to know that the fish have been genetically modified. AquaBounty, the company that has developed the fish and is applying to the FDA to market it, says that genetically modified salmon have the same flavor, texture, color and odor as the conventional fish.

In preliminary analysis released ahead of the hearing, the FDA agreed with the company, saying there were no biologically relevant differences between the engineered salmon and conventional salmon, and there is a reasonable certainty that no harm will come from its consumption.

Dr. Michael Hansen, senior scientist at Consumers Union, the publisher of Consumer Reports, testified that his organization disagrees with the FDA that genetic engineering itself does not constitute a material difference in the two fish. He added that the agency does have the authority to demand the labels.