The last time I was in Australia a friend in Melbourne introduced me to a very Australian dish: barramundi, or giant perch, a fish that’s native to the country and one I’d never encountered anywhere before.

It’s a big ‘un. The one at the top is lazing around in a tank at Sydney Aquarium at this very moment, and looks to me not a lot short of the maximum size this fish reaches - namely 1.8 metres in length. It was also incredibly delicious - and happily the kind of fish, I was told, that didn’t freeze well, so eating it fresh was the only option.

I went back to the UK and soon found my Aussie mates were barramundi fans too. Then, out of the blue, a bunch of the things turned up on the counter at Tesco (not a place I like to shop but I was in a hurry). These things weren’t much bigger than a trout and had been raised, it said, in the New Forest, presumably in a lake set aside for the purpose.

Naturally, this being Tesco, they cost a fortune, about £4 per fish if I recall correctly. They also looked long dead and with those opaque black eyes that should deter any fish buyer. So barramundi is no longer simply an Australian species. In the UK we’re so short of the overfished natural species we used to eat - cod and haddock mainly - that we’re bringing in foreign stock and raising it in ponds in the wood.

Maybe it tastes wonderful. But will it be like Australian barramundi? I doubt it somehow. The real barramundi needs brackish water to breed, not muddy lakes. Also it’s just… bigger. But this is what fish eating means in the UK today. The next time I was in UK the freshest fish on the counter was something called ‘Vietnamese cobbler’. In reality this is a kind of catfish raised in the Mekong Delta. So to make up for the fact that British trawlers have fished out the north sea we’re now flying in unknown fish from south east Asia and raising Australian species in pits in the woods.

The funny thing is that if you go into a fish market in Italy you’ll find plenty of produce on show, all of it local, and pretty much all of it European. What’s the difference? The Italians are willing to pay what it costs for good, fresh fish. And the Brits aren’t, so we buy whatever comes along.

It’s an odd, odd world. I live just twenty miles from the English Channel. Finding a good fishmonger is a real battle. Cross the Channel to Boulogne and you’ll find them everywhere - most of them selling fish that was caught in British waters then exported to French buyers who are willing to pay the market price.

It’ll be nice to try barramundi again in Melbourne. I think I’ll regard it as a treat to be enjoyed in Australia and nowhere else. Funnily enough my first panel on Thursday at the Melbourne Writers’ Festival is about food and literature. Don’t worry… I won’t mention Darling Harbour, promise.