Rainbow trout have done wonders in popularising fly-fishing. But these Yankee imports have bullied out our native brown trout on many rivers, made fly-fishing as easy as catching guppies and produced the instant-record fish.
H T Sheringham, angling editor of the Field in the early 1900s, wrote many articles about his quest for an 8oz trout. He caught hundreds at 4oz and quite a few of 6oz but those half-pounders were red-letter day fish. Nowadays, trout anglers scoff at waters that stock with anything under 2lb.
A 16-year-old in my village who has just discovered fly-fishing visited a local lake yesterday. When I asked how he had got on, he replied: 'No good; I had five but the biggest was only 3lb.' For years, I did not know that 3lb trout existed.
It is easy to understand his complaint, though. There are now more than a dozen waters in Britain that hold rainbow trout over 20lb. The new breed of trout angler expects a high average size and the chance of a 10-pounder, at the very least. No wonder the British Record Fish Committee has just been forced to set up two record lists - one for wild fish, one for those bred in captivity.
Chris Poupard, the director of the Salmon and Trout Association, said this week: 'It would have been a disaster if the committee had not agreed on two lists.'
Huge advances in farming techniques have enabled fishery owners to buy instant records, not just for rainbow trout but also for our native brown trout and even for salmon. A natural fish is now classified as one that has spent at least two-thirds of its life in the wild, which will not be as hard to prove as it sounds.
The heart of the problem is that it is easy to produce rainbow trout (just look how cheap they are in your local supermarket). An efficient farm can grow a rainbow from egg size to 6lb in a year, thanks to genetic selection and high-protein food. Rainbows are aggressive (hence those problems for the more docile brown trout) and greedy. At fish farms, the mere pretence of throwing out food is enough to bring trout to the surface, looking for lunch.
Now imagine what happens when those fish are first put into a river, reservoir or lake. They have all the natural caution of an Italian scooter rider, and about as much sense. There is no need any more to match your fly with a hatching insect, the very essence of fly-fishing. Watercraft and entomology are less important than being on the lake first.
The flies, if they can be called that, look like insects contrived by a punk rocker on LSD. No longer are they tiny, delicate imitations.
A typical one is the size of half a blackbird. And flies that once carried evocative names such as Greenwell's Glory are now called Baby Doll and Dog Nobbler. Once seen by many as the purest form of angling, fly-fishing has all too often become as artful as train- spotting. Oliver Kite, one of the sport's greatest exponents, put it very well. 'You throws it in, you pulls it out, and when you can't, you've got one.'
Maybe it is unfair to blame rainbow trout - overweight, oversexed and over here - for all this. Perhaps we should look more at our own motives for bigger and easier fish at any cost.
But they have certainly spoilt the magic of 1 April, traditionally the start of the trout season.
Although fisheries limit catches, it is common for a competent angler to capture his limit within 30 minutes. When you are home in time for breakfast, there is suddenly no excuse for not digging the garden or cleaning out the garage. And I cannot forgive rainbow trout for that.