Slovenia: You should have seen the one I caught on the Trebuscica

Slovenian marbled trout inhabit the rivers of the Soca Valley. Encounter the species that nearly got away

Oooh! Come here darling," crooned Nerys. She was trying to land a Slovenian marbled trout that had just mistaken a bunch of hair and feathers wrapped round a hook for a hatching insect.

Oooh! Come here darling," crooned Nerys. She was trying to land a Slovenian marbled trout that had just mistaken a bunch of hair and feathers wrapped round a hook for a hatching insect. The trout, less interested in forming a personal relationship with the person spoiling its day, splashed around. Moments later the fish was to hand, swiftly unhooked and released. It scooted off without a backward glance.

Having spent three days drinking espresso and beer in Ljubljana, we were now fly-fishing the Trebuscica, a tributary of the Soca river in the astonishingly beautiful Soca Valley in north-eastern Slovenia. With a backdrop of snow-clad peaks, the green alpine valley, with scattered terracotta-roofed villages, remains warm. In Slovenia you can overdose on scenic views.

An idyllic morning had been spent working our way down the river, dry-fly fishing for both rainbows and the region's unique marbled trout. Almost as clear as the air, the pools were deceptively deep, the bottom perfectly visible, a hint of Radox turquoise the only indicator of their depth. Rainbow trout hung magically suspended in the water like flotillas of airships.

The larger fish headed the fleet, where they had the first choice of bugs carried down by the current. Progressively diminishing in size to the back of the pool, any upstarts pushing their luck were swiftly reprimanded and chased back to where they came from. Stationed apart from these fish roamed the kings of the pool. These huge fish ignored our paltry insect imitations, their smaller brethren more capable of satiating their larger appetites.

In the heat of the day we sacrificed a promising pool for a dip. After the hotel's packed lunch and a beer, we worked our way back upstream as the afternoon cooled. By the time we left, I had caught (and released) 20 good-sized trout.

If you are staying at the Hotel Hvala in Kobarid, you will be glad to let your fish go. When your waders are off, and the renowned restaurant's menu is in your rod hand, "Trieste style" fish of the day baked in sea salt is better than any trout.

Kobarid is probably better known by its Italian name Caporetto, the site of one of Italy's most humiliating defeats of the First World War. While I fished, Nerys visited Kobarid's museum, and the Italian trenches, high on the hillside, from where they fought through the bitter winter until the débâcle portrayed in Hemingway's A Farewell To Arms. It was during the First World War that the Italians introduced the brown trout into the Soca Valley. Was this gross misuse of military funds, or a cunning strategy? "Let's put lots of fish in the river, then when the enemy are all busy fishing, we'll take them by surprise!"

Unfortunately, the more prolific brown trout was able to breed with the river's unique marbled trout, or marmorata, which can grow to a tremendous size. The two species became so mixed that the Slovenes thought they had lost their marbled – until 50 years ago when, above impassable waterfalls in a tributary of a tributary, an isolated colony of pure marbled trout was discovered.

A successful hatchery programme began in 1989 and the marbled trout is now thriving as a pure species again, with specimens reaching 55lb. Visitors' day ticket fees support the Angling Club of Tolmin's hatchery programme. This, combined with an enlightened code of barbless hooks and a modest bag limit, ensures that their 100 miles of the Soca and its tributaries operate on a sustainable system that secures the river's future. The river is expected to improve.

The Soca Valley has been farmed traditionally (with the exception of some fertiliser). The result is a vibrant habitat of wild flowers, thriving insect life and clean rivers that illustrate the devastating impact modern farming has had on our environment back home.

After a couple of days we moved up the valley to Pristava Lepena. Here owners Milan and Silvia accommodated us in a stone and wood house, part of a very mellow operation they run in a meadow surrounded by snow-capped peaks. We both fished. Nerys, after a day's instruction from Ernest, a local guide (be sure to book Ernest in advance), did so with considerable success. Later (in preference to walking, white-water rafting, canoeing or drinking in the sun) she opted to ride pure bred Lipizaners, and had an affair with a big black horse.

We both have something to go back for.

The Facts

Getting there

Three nights in a three-star hotel in Ljubljana costs from £322 per person, including return flights, transfers and b&b accommodation, through Slovenija Pursuits (08702 200201; www. slovenia pursuits. co.uk).

Being there

The Angling Club of Tolmin ( www.ribiska-druzina-tolmin.si/english.html).

Further information

Slovenian Tourist Office (020-7287 7133).