"Let me have a pound of that pollock, please."

"No, that's Boston blue . . . we don't have any pollock."

"Okay. Well, I'll try some of that flounder over there."

"Sorry, that's sole; the flounder isn't in yet."

"Hmm . . . Do you have any sea trout?"

"Sure, there's some weakfish right here."

If you buy a lot of fish in different places, the above scenario probably is familiar to you. Buyer and seller are talking about the same fish, but neither knows that.

Not surprising. With more than 400 species of fish off the North American coasts, nobody -- absolutely nobody -- knows every popular name of every fish. And with seafood becoming so popular that mongers can sell almost anything that swims -- per-capita consumption rose a record half pound in 1984 -- the situation is becoming increasingly confusing.

In an effort to clarify matters, the people who sell seafood are looking to stress the qualities of various fishes instead of their names. They hope to do this by creating "edibility profiles."

If, for example, you've always bought cod but the store has none, you could be offered a fish that looks, cooks and tastes similar, called, simply, North Atlantic whitefish. It might be almost any small, white-fleshed fish from the area.

The approach was designed with the idea that "at least the consumer will know how to cook the fish," because he or she is familiar with its type, says Bob Arnold, director of marketing at the National Fisheries Institute (NFI) in Washington. Arnold believes that if cooks are comfortable with fish, they can prepare it well. "The confidence factor is key," he says. "If people know that they can cook a type of fish, and it's fresh, they'll enjoy it." What difference does it make what you call it?

Roy Martin, NFI's vice president for science and technology, says the new approach to fish identification has been a long time coming. "Many years ago, a group of us discussed the problem of naming fish -- you've got whiptail, croaker, hokey, cancer crab, suckers, spots -- and said, 'If the world is going to be a hungry place in the future, we need an approach to nomenclature that makes some sense.' "

Some fish marketers have gone about this themselves, giving fish attractive handles when they feel the traditional ones turn consumers off. This explains the switch from pollock, an eminently edible fish that somehow got a bad reputation, to Boston blue, an appetizing name if ever there was one. Similarly, the Alaskan fishing industry is appealing to the Food and Drug Administration (FDA) to allow it to refer to Alaskan pollock by the delightful name of "snow cod."

Another way some fishmongers have dealt with all the confusion is simply to sell one fish under the guise of another; few of us could tell the difference between haddock, cod, hake, even pollock, no matter what they were called.

But the National Marine Fisheries Service wanted a more comprehensive and legitimate system. So they hired what Martin calls a "wordsmith" to develop a new approach.

The result is the edibility profile, which considers several characteristics -- taste, overall looks, texture, color, oiliness and water content, for example -- and enables comparison of fish. Martin hopes this approach will "allow us to group certain species according to these edibility profiles and give the fish some generic names" (no existing names would be changed). "We'd then be presenting a body of data which would help consumers to know how" to prepare any given fish, based on previous experience.

Arnold envisions charts and graphs of edibility profiles that would help consumers compare fish, in the store, based on quantitative measurements. "When you look at a profile of cod, for example, you might see it jag out on firmness and drop down on water content. If a store doesn't have cod when you go, you could look at the edibility profiles of what they do have and look for something similar," Arnold says.

Thus, a fish might not even be in the same family as cod. But you could take it home and cook it as if it were cod, with satisfactory results.

The edibility profile plan is in the early stages, with National Marine Fisheries labs in Gloucester, Mass., Charleston, S.C., and Seattle now gathering data on the 400 species of the seas. This is no mean feat, according to Martin: "There's no other protein source as complex as fish. Beef is beef and chicken is chicken, but seafood gets complicated very quickly."

The FDA, which rules on food names, has been involved at every step of the process. "They don't always agree with us," Martin says, "but they know what we're doing."

Meanwhile, an Army laboratory is setting up a series of test methods for each of the edibility characteristics. When all the data have been collected, they will be run through a computer to see how the fish group. "There may be some that don't group at all," Martin predicts. "But the final phase will be sorting and grouping, then developing a handbook for consumers."

At that point, presumably, we'll all feel comfortable asking for some of that North Atlantic whitefish, knowing that it may not be cod but that it will be similar enough to satisfy us. Buying fish will lose some of its folksy flavor, especially for those of us who've made a hobby of trading different fish names in different towns (I've got more than a dozen names for monkfish). But it'll be a lot easier.