The Stream Doctor

September 13th, 2004

Email YOUR Questions directly to the Stream Doctor. This is your opportunity to get an experts professional opinion on anything stream related.

Q. I live in Goderich, Ont. Can. I was walking in our local Maitland River this week. I found a bright blue crayfish. I've spent quite a lot of time in this river and have never seen anything like it. I have tried to get information at our local resource centers, but have been unable to find out anything about my blue crayfish. Could you please help me find some information, as I think blue crayfish are pretty rare in our area.

A. I looked up what I could find about crayfish coloration; the following information is from Pennak's "Freshwater Invertebrates of the United States," 3rd. ed. He says that crayfish normally range from blackish through brown, red, orange, green and occasionally blue. He further states that newly molted animals are usually brighter in color than those who have accumulated silt, dirt, and other material to dull their color. Often, crayfish closely mimic the color of the substratum where they are found, but this obviously takes time to develop.

Thus, although you obviously haven't seen many blue crayfish in your region, this color is not unusual.

If you have a question, please feel free to contact me.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to anything stream related directly to him for use in this Q & A Feature at

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