Food companies fighting a congressional directive to start telling consumers whether the fish they buy was farm-raised or caught won a six-month reprieve yesterday from the Agriculture Department.

New regulations to implement a provision in the 2002 farm bill requiring fresh and frozen fish to carry labels specifying their origin were issued yesterday, but the government said grocery stores won't have to comply until April. The labels also will have to specify a seafood's country of origin.

Food companies and trade groups had complained that processors would have to throw out stocks of fish if they could not sell them before the requirement took effect.

The delay will let the industry sell its existing product, the Agriculture Department said. Officials said they also plan to defer for a year strict enforcement of the new requirements while commercial fishermen, fish farmers, importers, distributors and retailers are trained on compliance.

The labeling requirement was supported by the commercial fishermen and operators of fish farms, who say consumers will prefer domestic to foreign product. It was opposed by retailers and other food handlers, who say the record-keeping will be burdensome. Both sides say the department gave them only part of what they wanted.

Under the rule, supermarkets and larger retailers will be responsible for the labeling but smaller mom-and-pop retailers will not have to comply, said A.J. Yates, administrator of the Agricultural Marketing Service.

The rule also exempts processed fish, such as canned tuna, breaded fish sticks and smoked fish, Yates said. Processors commonly mix fish from many sources, and "it's virtually impossible to specify where each can of fish came from," said Linda Candler, a spokeswoman for the National Fisheries Institute, a seafood trade association.

The labeling requirement does not cover fish sold in food service establishments such as restaurants or the salad bar and deli sections of supermarkets, Yates said.

Labeling with the country of origin should produce more sales for U.S. fishermen, said Deborah Long, a spokeswoman for the Southern Shrimp Alliance, a coalition of shrimp boaters based in Tarpon Springs, Fla.

"If they could enforce it tomorrow, that would be much better for the U.S. shrimp industry," she said.

The record-keeping requirements also could help food safety investigators trace outbreaks of food-borne disease, said Caroline Smith DeWaal, food safety director of the Center for Science in the Public Interest, an advocacy group.

While charged with enforcing the new regulations, the Agriculture Department also saw scant value in the law's labeling requirement, Yates said.

"We have been able to find little tangible evidence that consumers state a preference for country of origin labeling, and [that] it will lead to increased demand for U.S. commodities bearing a label," he said.