Well, I have heard untold numbers of discussions on this, taken part in more
than a few, and read a great deal about it, including weighty scientific
tomes and treatises, but to be perfectly honest, I think the problem lies
elsewhere.

There is no way to know what a trout sees, even assuming our eyes were the
same, or that it is possible to theorise based on eye construction etc etc.
Images are engendered in the brain, and there is no way to simulate that, or
even theorise about it much. What animals experience in the way of thought,
perception etc is ( at least for now, and perhaps forever! ) beyond our
comprehension.

In my opinion, the main problem is that people concentrate on both naturals
and artificials, but in the HUMAN environment. This is not where they are
used, or seen , or taken by the trout. If you observe these things under
the same conditions that the fish see them, then quite a number of things
immediately become apparent. The first is, few of the patterns extant
resemble the naturals much, IN THE CONDITIONS UNDER WHICH THEY ARE USED!
Secondly, very few people know how these creatures behave. Most of the
anglers and dressers I know don´t even bother doing simple things like
testing their flies in a glass of water!

There we have the two main problems. They are attempting to imitate
something although they don´t know what it looks like, and they also don´t
know how it behaves.

Many people use all sorts of patterns, some good, some more or less useless,
and catch fish, But not even a small percentage of these people has ever
seen what they are trying to imitate under the pertaining conditions, or how
it behaves. These are the main reasons why some anglers catch a lot, and
others very little. Other factors are of course important. Recognising a
hatch as such, and for what it is. Knowing when and how to fish certain
patterns, even when there is no obvious activity. Recognizing certain
behaviour or signs on the water, watercraft, etc etc etc. Luck does play a
part of course, but it has nothing to do with fly choice! Or at least it
should not have!

At any rate, all these things, luck included, are not much use unless your
lure looks and behaves as it should!

People have argued with me in the past, that it is essential to know how a
trout sees. I disagree, it is essential to know what the things the trout
take look like, and this is to a considerable extent independent of how the
fish see them. This is only possible if you see them under the same
conditions to which they and the trout are subjected. It has been proven
time and time again, to my own and many other people´s satisfaction, that
lures which look and behave correctly catch more fish. So I think the
problem does not lie with what the trout sees, but with what WE DON`´T SEE
!!!! Mainly for lack of looking!

Regards and tight lines!

Mike