Trout's Vision

**Walshmiko** · 12-08-2009, 08:36 PM

I was reading an article about trouts vision and I found it insightful. you see trout can see every color of the spectrum although rainbow trout are more sensitive to the blues,greens and reds but with age and adulthood the ability/or sensitivity is lost.. Rainbow trout tend to feed heavier on clear days then there low light cousins(brown/brook) Which feed more regularly at night or under low light conditions..

**Toad Hunter** · 12-08-2009, 10:13 PM

Interesting. Where did you find this?

Mike

**AaronJasper** · 12-09-2009, 09:22 AM

I can agree with the assessment on rainbow trout behavior as I have observed the same things. I will add more after work

**Magnet** · 12-09-2009, 01:25 PM

Rainbows love the TPO fly of the month known as the "firefly". The orange colored bead is derivative of yellow and red. Does yellow fit into the attractant criteria for rainbows? Interesting also Walshmiko is your point that trout may loose their ability to disern color as they mature. What are the implications that we need to consider with this in mind? The mature trout must still see intensiity of color shouldn't they?

**Walshmiko** · 12-09-2009, 01:44 PM

Yes they still see color, but the "sensitivity" to the ultra violet spectrum declines.. The desire/will that younger fish have the adults lack.. This is just something I read. I tied both the fire fly and lighting bugs for the record

**Silver Creek** · 12-09-2009, 02:22 PM

[quote author=Walshmiko link=topic=3853.msg29814#msg29814 date=1260319005]
I was reading an article about trouts vision and I found it insightful. you see trout can see every color of the spectrum although rainbow trout are more sensitive to the blues,greens and reds but with age and adulthood the ability/or sensitivity is lost.. Rainbow trout tend to feed heavier on clear days then there low light cousins(brown/brook) Which feed more regularly at night or under low light conditions..
[/quote]

I have read that rainbows see blue the best, and that all salmonids see blue the best. There is a fly called the Patriot, which is modified Royal Wulff which is supposed to be a great Rainbow Trout fly. I've tied some up and I found no difference. However, I've only tried it on planters.

I'd also like the reference to Rainbows losing the ability to see colors as they age. I've not read that anywhere.

Another point is that when your reference says rainbows are sensitive to blue, green and red, they are essentially saying that fish are sensitive to our entire visual spectrum. Remember ROY G BIV from high school physics? The visual spectrum is Red-Orange-Yellow Green Blue-Indigo-Violet as we go from lower to higher wave lengths. Some fish also see into the Ultra Violet and Infra Red spectrum which we cannot see.

So I don't understand how someone can say a rainbow is "more sensitive" to certain colors and then name the entire spectrum. It makes no sense to me. I think what they are saying is that fish have three different types of cones, the structures that respond to a certain wavelength of light. I've read that fish have 3 sets of cones - Blue, Green, and Orange/Yellow. Of these cones, the blue ones are most sensitive.

In talking about color vision in fish, the fish cannot see a color in our fly if that wavelength of light is not present in the water that they are in. By that I mean that if a color is not present in the light, it cannot be reflected from the fly to the fish. In another post about shadows on the water, I mentioned that water absorbs and scatters light. In clear water, the lower wavelengths disappear first as we go deeper so red is the first to disappear.

In general we fish 4 types of water. One is clear water relatively shallow where the light contains all the wavelengths. Deeper water may be blue or green. So the fish can see the blue or green. The color red in our flies would look black or grey because there is no red wavelength left. Sometimes we fish discolored water that is brown or red brown. This is common in Wisconsin because we have a lot of tannin in our water from cedar swamps. An underwater fly at depth that has blue and green in it would change to grey or black depending on how much green and blue wavelengths are present at that level of water.

So background color of the water is important in how the fish sees our flies. That is why Black and Purple work so well in bass fishing. Black forms a strong shape or silhouette. Purple being a very short wavelength has the greatest energy and is the last wavelength in our visual spectrum to disappear.

The color a fish sees is not as simple as looking at the color of our flies. It depends on the depth of the fish and the dissolved minerals and suspended material in the water which act as a filter to remove specific wavelengths of light from the fish's environment.