ON THE STATEMENT THAT trout have decreased in size I shall say but little. Its truth seems generally accepted; and the cause of this decrease is, by most writers, attributed to over-stocking the water. This may, in some cases, be the chief cause, but suitable water, food in plenty, and quiet shelter are all conditions materially affecting size. Moreover, the largest fish are rarely caught with the fly; and it may well be that trout give up fly diet and take to cannibalism and other evil courses, at an earlier age now than formerly. And this leads me to the last proposition I have to consider, namely:—“That trout do not rise to the fly as freely as they did.” The consensus of opinion on this point seems so strong that I think we may admit the fact and seek its cause.

I have little doubt that the primary cause is hereditary vice. We have seen that the angler in most streams is dependent on the artificial propagation for his stock. The largest trout obtainable are selected as parent fish, because the larger the fish the greater the quantity of ova or milt it contains. Fish caught for this purpose are usually taken in nets from deep holes, weir pools, and hatch holes—places teeming with aquatic animal life—full of minnows, stone-loach and bullheads, crayfish, fresh-water shrimps, and other crustaceans relished by trout—but these places are not suited for the development of the larvæ of water-bred flies. The parents of the fry or yearlings turned into our streams were, therefore, in all probability, bottom or mid-water feeders, rather than surface feeders; their diet consisting more often of fish, snails, crustaceans, and submerged insects than of floating flies. At any rate, they must have escaped the flies of the angler to have lived long enough to be caught in the net. It is probable that the fry inherit the taste of their parents; and this taste is confirmed by education. As soon as the contents of the umbilical sac are absorbed, and the alevin becomes a perfect fish, the first food presented to him is liver and dog-biscuit, minced fine and passed through a sieve, and of such is his daily food until he is transferred from stew to river. Here he has to shift for himself, and he naturally continues to seek his food, as heretofore, in mid-water, not on the surface. And should he, once in his life, out of mere curiosity, or in the true spirit of empirical research, be tempted to taste the angler’s fly, he returns to the water a sadder but a wiser fish, henceforth to preach and practise the maxim, “In medio tutissimus.” Although I have used the word preach more or less in a spirit of playful exaggeration, I have used it deliberately; being convinced that fish have some power of communicating with each other. I must not enlarge on the subject here, but I will mention two facts that would seem to confirm my belief.

Two plates from Blacker's Art of Fly Making (1855).

If a fly be cast in one of Mr. Andrew’s stock-ponds at Guildford, there is a rush and a fight for it amongst all the trout within whose range of vision it falls. If it be cast again, a few minutes after a trout has been caught and returned to the water, two or three fish only will compete for it. Repeat the process, and perhaps one may come, slowly, shyly, and in a half-hearted manner. But when several have been taken and returned—although the pond is large and crowded with fish—cast the fly where you will, the trout are shy, suspicious, and hard to catch.

The next case I shall pray in aid must be within the experience of many fly-fishers. When trout are busily rising on a long shallow which is bare of weeds, it often happens that, on nearing the water with eyes fixed on a fish you hope to catch, creep as you will, you disturb another lying, perhaps, hidden from view under your own bank, and of whose presence you first become aware on seeing the wave he leaves behind him in his wild rush up the whole length of the shallow to the pool above. Every trout he passes joins in the flight. It is a case of sauve qui peut. And for the next half-hour the angler might as well fish in the highroad as on that shallow. But let the same fish swim over the same shallow at the same pace, when he is engaged in chasing another fish, or on private business, and is merely hastening his pace of his own free will, and not a single trout unless it be directly in his path, will leave off feeding, or take the slightest notice.

But to return to heredity and education. If there be any truth in this theory, it might be well to catch the parent fish with the fly, and to feed their offspring in the stews, as far as possible, with floating food, thus teaching the young trout from early infancy to look towards heaven for his food, instead of grovelling for it at the bottom of the water.

The late Basil Field, a deeply respected expert on this topic, was elected to the presidency of the Fly-fishers’ Club (now known as the Flyfishers’ Club) three times. This article first appeared in No. CCCXXVII Vol. LV, N.S. (1894). It has been manually transcribed exclusively for this New Series, with very minor edits to track usage. Copyright on this version is claimed. To obtain the unedited text, please see the copyright page for instructions. Please note the Fortnightly Review and fortnightlyreview.co.uk in citations based on this transcription.

Additional resources of interest: Dr Andrew Herd’s A Fly Fishing History. Waterlog Magazine and the Medlar Press publish related content.