Hatchery Trout Coloration and Diet

[FarmerDave]

pcray1231 wrote:
The pigments which cause the brighter coloration are actually pretty lean in mayfly and caddis diets. Fish that subsist on them tend to be paler in color.

And baitfish eaters tend to be more silvery.

Freshwater shrimp, cressbugs, sowbugs, and crayfish, though, are very rich in pigments. Anything with a shell, basically. These foods give that bright red stripe on rainbows and the reds and butter colors on browns. I believe stoneflies also have quite a bit.

Pat is once again spot on.

It's the same reason some flamingos are pinker than others. They actually all start out gray or white and turn pink (to varying degree) from alpha and beta carotenoids in their diet. Crustaceans tend to have higher levels of this.

We all know this effects the coloration of fish flesh, but I'd argue that it effects skin and scale pigment as well.

Troutbert, I cut my teeth on infertile freestones and in my experience they all tended to have poor insect live (relatively speaking), but strong populations of crayfish. Crayfish do tend to be sensitive to pollutants, but apparently they can handle infertility and fairly low PH similar to ST.

IMO, another thing that can effect the coloration is the stream chemistry. Some streams tend to produce brook trout with more of an orangish red belly while others had more of a pinkish red. I always guessed that this shading is a result of iron or tannic acid content in the stream. One stream in particular stands that I occasionally fished as a young man, always produced very dark brook trout with a deep pinkish red (maroon) belly. This stream is an undisturbed class C at best that flowed through posted land which was heavily shaded with mature hemlock. The dark color was likely due to lack of sunlight, but I always assumed the shade of red was influenced by stream chemistry.

 

[gulfgreyhound]

Skin pigmentation is genetic.imo. I think stocking has mixed the Gene pool and produced some changes in the skin color in trout. I've seen Browns that rival any trout in coloration. Some of the browns that I've caught from lake Ontario are just beautifully golden with great red and black spots on their sides.
Dark fish from dark shaded streams are probably just exhibiting Phototropism in response to the dark surroundings? GG

 

[FarmerDave]

Minor correction to my previous.

I knew that crayfish are sensitive and usually one of the first thing to go when a stream or pond is polluted. So, why was I finding crayfish in tiny infertile streams that contained no trout, and in some cases no fish at all.

I did a small amount of online research and found to my surprise that Crayfish are less tolerant to low PH than brook trout. I looked it up (that is the minor correction). It wasn't a scientific article, but I'll accept it as true. Sorry about that Troutbert.

So, I dug a little more to find evidence that supports my own observations.

I stumbled across this.

No fish, but crayfish in infertile acid streams?

I feel much better knowing that I wasn't talking out of my butt. ;-)

Apparently there are other factors?

 

[mcwillja]

I fish almost exclusively on the Delaware system now and the brown trout there are butter yellow and most of the insect life on that river is caddis and mayfly. I am not sure i agree with the notion that mayflies and caddis flies don't give fish pigmentation. The rainbows on that system are as colorful as you will find and i have never seen a cress bug or scud in that system. Not saying they aren't there but its dominated by mayfly and caddisflies and the fish have vibrant colors. There is a strain of silvery browns in there but i think it's more the species of brown than it's diet.