Since the Fifties, when the first trout farms sprang up in Britain, trout farming has grown and grown. Though we may not eat as much trout as salmon (around 158,000 tonnes of which are now farmed in the UK), trout farmers still raise around 16,000-17,000 tonnes of the main farmed breed, rainbow trout, every year.

Are any other breeds farmed?
Although the rainbow trout dominates, there is some farming of brown trout, which are indigenous to Britain’s rivers and lakes and, as their name suggests,tend to be brownish with red and black spots. The salt water variety, sea trout, live in coastal waters and can grow up to 1.4m.

Should you buy organic?
There is debate about whether fish can ever really be classified as organic due to the nature of their environment, but if you want assurances that the trout have space to swim in and aren’t given antibiotics, and that their food doesn’t contain anything artificial, organic is the way to go. Non-organic feed contains a colouring so that the flesh turns deep pink, organic fish have much paler flesh – within the trade they are known as “white” trout, says Tony Free of Purely Organic, based at Deverill Trout Farm in Wiltshire. Free farms rainbow trout, and some brown trout, in pristine waters that flow through his neighbour’s organic watercress farm. On its way through the watercress beds, it collects freshwater shrimps, which the trout eat, giving a pale pinkness to their flesh. “It’s much more natural to eat this than pellets containing carbohydrates,” says Free. He believes it helps give the fish profound flavour, redolent of trout as it would have been 50 years ago, when the population was mainly wild.

Is there such a thing as a truly wild trout any more?
“People assume when they see trout in a river that it must be wild,” says Free. “But the reality is that, apart from a few streams in Scotland where this may still be true, most trout rivers and lakes have been stocked. Instead of males and females, almost all rainbow trout and about half of brown trout are either ‘triploids’ or ‘all-female’ fish. In triploids, the embryo is treated to give the fish an extra ‘X’ chromosone: the energy that would go into becoming sexually mature is thus channelled into growth. In the all-female fish, a female is fed testosterone until it becomes pseudo-male. Its sperm produces all-female offspring, thought to taste better.”

Where to buy
Purely Organic, Longbridge Deverill, Warminster (01985 841093; www.purelyorganic.org.uk).

Readers’ queries

I’ve bought an espresso machine and want to experiment with different coffees – where can I buy by mail order?

Union Hand Roasted is a pioneer of ethically traded coffees (020-7474 8990; www.unionroasted.com). The Monmouth Coffee Company also specialises in unusual coffees from single estates, farms and co-operatives worldwide (020-7064 4950; www.monmouthcoffee.co.uk).

If you have a food query, e-mail food.detective@thetimes.co.uk

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