A story about the metric system yesterday erred in stating that the Agricture Department was planning to label all fish and poultry products in metrics. The department did request public comment on metric labeling, but has no plan to require such labeling.

George Washington suggested it back in 1790. Gerald Ford gave it the official presidential seal of approval two years ago. Henry Ford measures his automobiles by it. And the Treasury Department even allowed it to replace the venerable fifth of whiskey.

Everybody, it seems wants the metric system here in the United States - except the American public.

After an initial flurry of "think metric" publicity marked by the signing by former President Ford of the 1975 Metric Conversion Act there has been some hasty rethinking on the part of federal officials who once predicted an easy shift from the reigning system of pounds, feet and gallons into grams, meters and liters.

"It's slow all right," concedes Jeffrey Odom, metric coordinator for the Bureau of Standards, which is charged with overseeing the official conversion of the country to the metric standard. "When people are comfortable with something they aren't about to rush and switch things around."

That may be understating the problem slightly:

When the Federal Highway Administration last year called for comments on its plan to spend about $100 million converting all the nation's highway signs to metric: 5.000 letters poured in. About 2 per cent favored the idea and the rest didn't. The agency shelved its conversion plan last June.

"We got the message," said James Crowley, the federal high-way official who was to be in charge of the program.

A similar phenomeon took place when the Department of Agriculture decided to seek out public reaction to its plan to label all fish and poultry products in metrics. USDA officials were surprised at the negative reaction among the 2,000 mostly anti-metric letters that were sent in. Again the conversion plan was consigned to limbo.

The National Westher Service also held up its plan to convert From the Fahrenheit system of temperature measurement to the Celsius scale after opposition from letter-writers. The weathermen will re-evaluate their decision to go metric next year, spokesmen for the agency said.

Opponents to the metric conversion are rarely organized, according to federal officials, although the heaviest opposition seems to be in the Midwest, the Southwest and New England states.

The number of those who oppose the idea of U.S. conversion to metric appears to be growing. A Gallup poll last month indicated that there was a nearly 2 to 1 opposition to conversion compared to a poll four years ago that showed most people who knew about the metric system favored it over the current system.

"It's kind of funny," said federal metric coordinator Odom. "Before the Metric Conversion Act was passed we used to get most of our letters from people who were all for the idea. Now most of the letters we get are against it."

Some letter-writers, he said, complained of the system as further federal intrusion into private lives while others demanded a national referendum on the subject. Some, said Odom, called it a Communist plot.

Opposite arose in other quarters when the Treasury Department's Bureau of Alchol, Tobacco and Firearms last year permitted liquor to be sold in metric sized bottles. Some dealers replaced the traditional fifth with 750 milliliter bottles - which contain two-tenths of an ounce less liquor - and sold them at the same price.

Some retails stores that have gone metric have also had complaints. "A lot of customers don't understand the system and son't like it. They also say it's un-American," said Chris Banthien. manager of the Clayton Coffee Co., a suburban St. Louis coffee and tea store that switched to metric sales in 1975.

The strongest opposition to the shift to metrics has come from Indiana, where a bill to force a statewide referendum on the idea was recently introduced into the state legislature. A similar bill is being planned for West Virginia.

Indianpolis attorney Robert F. Wagner said he had received 3,000 letters of support after he formed a group called Metric Rebellion, which opposes the national shift to the system.

"Someone has to ask the question about why we're doing this," said Wagner, 42. "Right now in the U.S. there's a tremendous resistance to the government doing anything more to us. When government suggests that a 200-year-old system that has worked fine isn't any good any more, well that just drives people crazy."

Wagner said he had received mail supporting his drive from persons across the country. He said he planned to take out ads in local papers to raise further support for the anti-metric cause. "I don't think people are going to accept this," he said. "The only ones who get anything out of it are the big corporations who have to convert and the government which has committed itself."

Actually, under the federal law signed by Ford two years ago, conversion to the metric system is voluntary. Originally federal officials had proposed a 10-year conversion timetable dropped for the country but the plan was dropped after some critics claimed it could cost up to $40 billion.

A Bureau of Standards official said, however, that once a formal U.S. Metric Board is established and approved by Congress it is likely some target dates for conversion will be drawn up.

The federal metric board was approved by Ford and President Carter nominated 15 prospective members in the proposed 17-person board in October.

Despite the slow progres of the conversion and the federal pullbacks, federal metric officials claim they are making headway. At last count, 32 state school systems have pledged to shift over to the system eventually and the American National Metric Council, a Washington trade group backing the idea, estimated as much as one-third of the nation's heavy industry is already converting. The auto industry is furthest long, a council official said.

"We're not really surprised that opposition is springing up." said Odom. "It's had to convince the man in the street of any immediate benefit from this for him. But we're far enough along now so that I don't see any chance that we'll go back to the old way."