http://www.flyline.com/tips_trivia/myths_legends_lies/
Myths, legends, lies and other fishing facts Flyfishing: 200 years of tradition unencumbered by progress. Repeat a lie enough times and what do you have? Another lie. There are numerous myths, legends and lies regarding trout and fishing for them. Here are a few to chew on:
1. "Eyes on streamers provoke strikes." It is widely held that predatory fish key in on and attack the eyes of bait fish. As "proof" many anglers cite the presence of ocelli or false eyes near the tail of some fish. They contend the predator will target these eyes and the attack will be directed toward the tail.
Studies around the world with numerous species of fish show that that predatory fish do not aim for the eyes. In every instance the mid section of the prey was targeted. The size, shape, location, presence or lack of the eyes (or ocelli) in no way altered the point of the attack.
Researchers have found that very often a predatory fish will not attack if the eyes are visible. Time after time bass, pike and barracuda have been observed rushing past available bait to take a fish with it's back turned. It seems predators have learned they can get the jump on their prey when it's not looking.
Ocelli located near the tail of bait fish may give the impression it is "looking" when its back is turned and avoid being attacked. For the same reason eyes on a streamer may actually be counter productive.
There is no doubt some flies are more effective with eyes than without. Eyes can add both physical and visual balance to a fly. The eyes may add just that certain bit of spark, brightness or contrast that makes the pattern irresistible. In certain patterns, eyes impart action and even noise to a streamer. Blanton's Whistlers and Clousser's Deep Minnows are good examples; exchange the lead eyes on a Deep Minnow with plastic eyes and the fly loses both it's jigging action and fish catching qualities.
2. "Approach from behind (usually from downstream) to sneak up on trout." From a human's perspective this makes sense; however, if we lived in a world of mirrors and our eyes were placed where our ears are, we might be less inclined to think this way. A trout's eyes are placed high on the sides of its head. Its blind spots are immediately in front of its nose and for a few inches directly behind its tail. A trout's ceiling is a huge mirror that allows it to see reflected images that are hidden from direct line of sight. In short, it's pretty darned hard to sneak up on a trout unannounced from any direction. Luckily, if approached with respect, trout don't care.
If we act non threatening, the fish will almost always accommodate our presence. An analogy most people can relate to is a deer in a meadow. You can walk quietly along the perimeter of the meadow and usually the deer will give a good stare then continue to browse with an occasional glance. If you stop and do jumping jacks, the deer will become a blur.
Move slowly, don't needlessly false cast or wear clothes that flap in the breeze. Watch the fish. When it starts to sink to the river bed, fold its fins or increase its rate of tail beats, stop whatever you're doing and allow the fish to relax. If it bolts, move into position and wait. The fish will usually return and begin feeding in short order.
3. "Small tippets are better because they are harder to see." This one defies common sense. Switching from a 5X to a 7X tippet is making a change of two thousands of an inch in line diameter. Do you really think trout can tell the difference?
A trout can see 7X tippet as well as it can see climbing rope. I spend hundreds of hours underwater watching trout feed. Very often the fish will be taking minute items such as daphnia or copepods that are impossible for me to see much more than a foot away. These fish routinely initiate their rise to the food when it is still five or six feet away. At that distance even I can clearly see 7X tippet, and have no doubt trout see it too. Luckily, trout don't care.
On Fall River and Fort Creek I've glued foot long pieces of 15 pound Maxima to Hexagenia mayflies and grasshoppers. These notoriously selective fish rose to the bugs without hesitation, yet they turned away from the same fly attached to 5X tippet connected somewhere upstream to a fly rod.
The difference, and the only difference, is drag. It is amazing how much junk is floating in the water in and amongst trout food. If the trout rejected every item near a pine needle or piece of straw, the fish would starve to death. Trout are not accustomed to seeing a mayfly spinner swimming upstream or an ant skating sideways.
The thinner the tippet, the less drag it is inclined to impart on the fly. You can also reduce drag by lengthening the tippet or by affixing the fly with an open loop knot.
4. "You must match the color of the prey." What a crock. Trout see every color we do, plus they can see infra red and ultra violet. When we see a green caddis larvae, we are seeing an object that is absorbing all the visible wavelengths of light except blue through yellow. These colors are reflected in a blend of light that appears as green to the human eye.
What if this caddis is also reflecting ultra violet? It'll still look green to us because we can't see UV. To the trout who can see into the ultra violet spectrum, the caddis will look something far different from green.
It is well known that many patterns, such as Bob Quigley's para nymph, work better when tied in purple rather than the PMD hatch matching yellowish green. To our eyes the imitation looks nothing like the real thing, however, the infra red reflecting qualities of the purple fly are better at imitating the natural as the trout perceives it. And that's what counts.
Out of a laboratory we have no way of knowing how trout perceive a bug. Luckily, it doesn't matter. Trout don't care if the fly contains the wrong color. Blend lots of colors into your dubbing . . . as long as the right color is present, most fish selectively discriminate against the wrong colors and take the bug. Whitlock's "bright dot" flies are a perfect example of this.
(article continues on at above link if you wish to read the rest..there's 10 total..most of remaining having to do with nymphing which is why they were omitted)
-MT