EATEN ANY good ratfish lately? Or mudblowers? Or redfish? Before you say no, pause and consider whether you have chosen from a restaurant menu or a fish store's supplies some creature with a more pleasant, though not a more familiar, name. If you have, it's possible that you may be participating in what amounts to an experiment conducted by both government and private enterprise to solve what is gingerly referred to as the "fish nomenclature problem."

Actually, the problem is not so much the unappetizing names of unfamiliar fish as it is the undersupply of familiar fish, according to a story by Pete Earley in The Post's Federal Report. Fish are distributed very unevenly in the seas and lakes, with vast concentrations in some spots where feeding conditions are good, like the Grand Banks, and no fish at all in the vast majority of waters, including, we think, some fishing spots that have been highly recommended to us. Fish supplies also vary widely from year to year, sometimes because of obvious overfishing, sometimes for reasons that are mysterious (as in the virtual disappearance of anchovies from the waters off Peru, a disappearance that nearly bankrupted that nation). For the past decade, supplies of the Atlantic fish chiefly sought by professional fishing fleets -- Arctic cod, haddock, flounder and herring -- have been dwindling. Professional fishermen, and also those who would like, for a variety of reasons, to see Americans consume more fish, have been trying to persuade the rest of us to eat other fish.

But who wants to eat ratfish or spiny dogfish or even shark? After all, although many southerners will have difficulty believing it, there are some people who still resist catfish. Responding to this problem, the National Marine Fisheries Service has urged restaurants to feature "edibility profiles" of unfamiliar fish, rating them on flavor, fat, odor, color, flakiness, firmness, coarseness and moisture when cooked. It has been tried out in five seafood restaurants in San Diego, apparently with some success. "The profiles," owner Craig Ghio says, "give customers a chance to see that shark, for instance, is a mild, dry fish that has a lot of the same taste qualities as halibut" -- not, we might add, what we would have expected at all.

The National Marine Fisheries Service, mindful perhaps of the Reagan administration's skepticism about government regulation, does not advocate standardization of fish names; and, given the wide variety of names used for the same species, that seems a reasonable forbearance. Sebastes Marinus, for example, is known as rosefish or redfish in the East, yellowfish in Portland, Ore., and, as a result of creative entrepreneurial renaming, ocean perch in the Midwest, "even though," as Mr. Earley says, "there are no perch in the ocean." There are, however, plenty of spiny ghostsharks, and we may be eating a lot of them soon -- if someone can just think up a good name.