SAINSBURY'S has taken a fish called pollock and re-invented it as a fish called colin. They have put the fillets in designer packaging inspired by the gaudy art of Jackson Pollock and is selling them as a version of cod.

When I read about this, I immediately checked the date. But April Fool was the week before last. The Sainsbury's logic is as follows: cod is scarce, cod is expensive. There is this cod-like species called pollock which is more plentiful and cheaper. (Sainsbury's insists on using the spelling pollack, which makes it sound like an immigrant fish from eastern Europe.) People, they say, are too embarrassed to ask for pollock or pollack, so they rebranded it as colin. Which is apparently a French name for pollock.

Being French, colin is pronounced colan. So instead of asking for a fish which sounds like bollock, embarrassed Sainsbury's customers can now request a fish that sounds like colon.

The hiring of a chap from the Red or Dead fashion company to design the colin fish pack would seem to indicate that Sainsbury's is taking the mickey or at the very least is in search, successfully, of some cheap publicity.

Frankly, I am not impressed by this fish sans frontieres. The pursuit of piscatorial delights is a serious business.

Sainsbury's is not the first to try to thrust pollock down our throats. Hugh Featherington-Parsley of TV's River Cottage fame not so long ago devoted many broadcast hours to trying to get our chip shops to flog this fish. I have yet to see a pollock supper on sale. Not even in Pollok, the people's republic on the southwestern approaches of Glasgow, which is the Buffer's ancestral home.

The Norwegians, who catch quite a lot of Atlantic pollock, have been trying to punt the stuff for years. A slight drawback is that the Atlantic pollock is a bit brown and grey (not just round the gills) and has not caught on. Alaskan pollock is whiter and more cod-like and has found its way into fish fingers, fish burgers in fast-food joints, and now as a fish called colin in Sainsbury's.

Pollock may be the new cod but I have managed to survive without it. There seems to be a sufficiently wide choice in the various fish emporia without resorting to colin. Not that I shop for fish in high street premises these days. At my local fishmonger, it's a case of pressing the nose against the window. Monkfish at £34 a kilo, lemon sole £28, cod fillet £18. I am spoiled by the market stalls of Barcelona, where you would have difficulty carrying home £34 worth of dorada, mero, merluza, gambas, calamares or pulpo.

There is something about a counter heaving with pescado and mariscos which stirs the blood. Perhaps it is because I am of fish stock. My mother was a skilled fishmonger. But it was a case of the cobbler's children being badly shod. Having gutted fish all day, the last thing mother wanted to do was bring her work home. The same applied to poultry. Her dislike of the business of removing the entrails of birds meant chicken was rarely on the menu.

I spend hours hanging around Spanish markets. There is something quite therapeutic about the business of going from stall to stall buying each item required for the dish of the day.

Quite often the dish of the day is behind the counter. I don't mean to be lascivious here but there is something quite feisty about women who work in Spanish market stalls. There is a lady at one Barcelona fruit stall who occasionally brightens up the day by doing a routine about handling her ripe melons. It's not so much shopping as being in an Almodovar movie.

The best bit is watching skilled fishmongers at work. When they have completed their intricate surgery, they give you not only the beautifully filleted or butterflied results, but most of the bones and bits of skin for making stock. Buy half a salmon and you get half the head to take away. I am sure there is an exquisite ancient Spanish dish involving half a salmon's head. My recipe is to leave the salmon's head in the fridge for a week and give it to a neighbourhood cat.

Back home in Glasgow, the closest to a Spanish fish market experience is to be found at the SeeWoo Chinese supermarket. Its fish is so fresh, many of them are still alive. It's not only a shopping trip. You can take the younger relatives along to look at the glass cases full of lobsters, crabs, eels and halibut and tell them it's a visit to the aquarium: Sea World at SeeWoo. There is a wide choice: abalone, brill, bream, bass, conger, cod, cuttle and so on through the alphabet. There is "fresh salmond" on the SeeWoo list but this is probably a misprint and not fillets of the first minister on a bed of rice.

Normally I do my shopping for fish in the less exotic setting of the Savoy Centre, a slightly down-at-heel mall in Sauchiehall Street. When I serve up my sea bass in pesto crust or a tagine of salmon and haddock fillets lightly scented in a charmoula marinade, or a piece of Aberdeen boneless simply grilled with butter, my guests invariably murmur appreciatively and enquire where I bought my fish.

This is my opportunity to extol the virtues of Frank's Fresh Fish at the Savoy. Somehow Frank manages to sell his stuff at almost half the price of the high- street shops. His quality is good, as you can tell by the number of pernickety Chinese customers giving the sea bream an extensive post-mortem examination.

Supermarkets tend to be a no-go area for fish. Even my beloved Lidl. I was once seduced by a pack of frozen mahi-mahi at 4p a kilo or some such ludicrous price. The mahi-mahi had been wafted all the way from the Pacific to Maryhill so I sought a recipe that would do justice to its origins. Soy sauce, lime juice, rice vinegar, sesame oil, dried red pepper flakes, slices of peeled fresh ginger all went into the mix.

What came out of the oven was a fish that tasted of mackerel. Not even an honest piece of mackerel slathered in olive oil with smoked paprika and some bits of wild garlic and grilled on an open fire as they do in a certain little restaurant in Barceloneta.

But a mackerel called mahi-mahi, tarted up in sesame and ginger. It was cheap fish by any other name. I suspect the same will be true of colin the pollock down at Sainsbury's.