Fishing Lines: My prehistoric prey from Ooble Oop

Trying to elicit important information from a diver who has not removed his mask, aqualung and goggles is one of journalism's tougher challenges. As a result of his answers, I can tell you that the biggest arapaima in the tank at Underwater World on Sentosa Island, Singapore, weighs around bloop blob blob, they have lived happily in the giant aquarium for about glugb years and originally came from Ooble Oop. That's when I gave up.

My interest in arapaima goes back nearly 20 years, when I pottered around the Ecuadorean jungle, trying to catch one. Since then others, notably the angling explorer Jeremy Wade, have been successful where I failed. But I've always retained a special place for this prehistoric creature, the largest scaled fish in the world. They are air breathers, adults coming to the surface for a gulp every 20 minutes of so. This makes them easy targets for natives, who have hunted them to the brink of extinction in some areas. Even their scales are used as nail files.

Arapaima are said to grow to 13ft and more than 500lb. The largest at Underwater World must have been close to 200lb, though in the absence of more accurate information, you'll have to accept my guestimate. Most come from the Amazon and Orinoco basins and Guyana, though there is a trend to stock them in Thai fishing ponds.

They are magnificent. The intricate patterns on their heads look as if they bear a message carved in a long-forgotten lang-uage. Their scales, olive edged with fire, are big as playing cards. You can imagine them 40 million years ago, hunting through some primordial soup.

Sorry about that lapse into whimsy. But catching one is still my big unfulfilled ambition. I got bitten by every flying bug, scared by tarantulas, terrified by vampire bats and almost killed by a fer de lance snake in my fruitless quest in the Ecuador rainforest, all for a fish. So we have unfulfilled business to settle. To see three of them cruising through an amusement island's tank was as startling as finding an anaconda hiber-nating in your garden shed.

In the absence of finding any fishing in Singapore, I had fallen back on the aquarium. When I had supper with Dominic, who runs Fishzone Singapore, a big-game boat, he told me that in season they could guarantee large numbers of sailfish less than an hour from shore in 50ft of calm water.

Normally, sailfish (plus marlin, dorado, giant trevally and cobia) live in very deep water. Not here. Catching them on light tackle in such shallow water would be very exciting. It was the old story: you should have been here last month, or next month. Any time but now.

Demand for fishing outstrips supply on Singapore. Dominic told me I could try one place that was a converted swimming pool. Another local hot-spot is a pond behind the municipal rubbish dump. I had the tackle, wanted to fish, but I wasn't that desperate.