There is no more fatuous question to be asked of a waiter in a restaurant than: 'Is this fish fresh?' In a lifetime of eating out I have yet to hear (for example): 'No, I'm terribly sorry, not really; sea bass is expensive, and we had no takers yesterday so . . . well, you understand.'

Is the 'catch of the day' really the catch of the day? Of which day? Daily I see the crustaceans (especially) and fish for which Sete is famous roar northwards in refrigerated trucks. Given the efficiency of the French food distribution system, I feel reasonably certain that within 24 hours that harvest will be in the market and on the table.

That is about the outside limit for freshness, though restaurateurs and fishmongers resort to some pretty tricks on this score, such as: tying head and tail together to create the characteristic arching of a fresh fish; constant spraying with water to reduce visible drying-out, the mark of putrefaction; scaling the fish down to the skin below to make it seem brighter; removing the eyes so you do not see they are dull; spooning chicken blood in the gills; even colouring the flesh with dyes. Oh, the tricks of the trade are endless.

The unhappy truth is that not many of us, shopping for fish or shown one in a restaurant, can actually tell fresh from foul. That is especially the case when we eat by the sea, and make the automatic mental adjustment that if the sea is that close, then the fish must come from it. Ha] This, I fear, is a myth. Anyone who lives by the sea, and certainly by the sea-as-resort, should be able to count the number of fishing boats that chug off into the waters at night; and if these are few (or nil, which is more likely) he can wait by the market and watch his fish being brought in by truck.

Oddly enough, my experience is that islands suffer most from this situation. Any idea that the fish you will eat on a Caribbean island is fresh should be abandoned. Places that live by tourism have no reason to engage in fishing. Those picturesque boats you see lying on the sand may indeed be used to catch fish, but those fish are eaten by the person who has caught them.

For though fish fetches a fine price, and is often more expensive than meat on a menu, fishermen do not get rich and are therefore an ever-decreasing breed, especially in the less industrialised countries. In 'advanced' Europe, fishing is an arduous and sometimes dangerous task. The market is capricious, transport and refrigeration expensive, competition exceedingly fierce. The result is that a trade that was once highly local, and on an island almost omnipresent, has become the domain of the wholesaler, who will often find it cheaper and more efficient to import than to handle local fish.

Can the wholesaler be blamed if the ultimate customer does not know enough to know when fish is fresh?

Here, then, is my guide, culled from many sources, as to how you can tell. First, some elementary facts. Within 20 to 30 minutes of being caught, or an hour or two if large, a fish begins to corrupt. Its backbone will rigidify but, as a fish rots from outside in, its flesh will still be solid. Then, one by one, the symptoms of decomposition set in:

If you press the flesh with your finger, you should leave no mark.

The scales should be bright, close-linked and attached to the skin, while the skin should be taut and humid, and should show neither crease nor laceration.

The eye (if you can look a fish in the eye) should fill the whole of its ocular cavity (it shrinks progressively as the fish goes off); its pupil should be large and black, while the iris, which in life is golden yellow, should not look bloodshot (exception made here for trout, bream and dentex which are red-eyed).

The belly should be neither swollen nor soft; it should be free of spots, whether grey, red, black or green.

The anus (forgive me) should be shut tight; the viscera should be clean, smooth and shiny. Lateral fins should be tight to the body; the backbone and its surrounding flesh one.

Smell is an excellent guide, when the nose is not being tricked by the fish being surrounded with seaweed or other marine odours. If a fish smells at all acid or disagreeable, pass it by. A fresh fish smells of the sea and seaweed, and the tell-tale spot for putrefaction lies in the gills, which should not smell too strongly. They are the first parts of a fish to show discoloration and to dry out.

In short, when buying fish or shown a 'fresh' fish in a restaurant, do not hesitate to become a pathologist; use your eyes and your nose. If we all did that, and refused fish that was not fresh, our supply would rapidly improve.