I was reading on various threds that crawfish are a favorite food for many octos. I have access to a stream that has many crewfish in it. My question is, how can I be sure that there are no polutants in the stream water, and therefore in the crawfish? Everything in the stream is seems healty, and the water is swift moving and clear, but how can you be sure?

well, you could take samples to your local water authority.

We have to do that on a regular basis at my work for all the streams and springs that feed the loch.

But to be honest you will not be able to ask them if its 'octopus safe'! However, if the local fauna is stable and doing well then you can guess it's not too bad.

May be worth while setting up a crayfish tank and putting them in a one month quarantine if it is a worry.

I recently raised concerns about feeder fish from shops and possible copper contamination.

C

wow, i never thought about the feeder fish that way, looks like i go to bobs bait and tackle for a few things, but i do have a LFS that i know the owner of very well that keeps a few octos himself, im sure he can direct me in the right way.

Crayfish only migrate a mile or so up and down a river/creek, so if there are no farms, feed lots, or mills more that two miles upstream, you should be fine.
Colin, unfortunately in the US, we have to take water samples to a private lab and pay some $. It shouldn't be more than 50 bucks or so though...
Greg

I think it is actually law here that you can demand a copy of a recent parameters test??? Need to check into that too :)

Ever heard of the Red signal crayfish from the US? Is was released in Scottish rivers a number of years ago by people who wanted to eat them.. they are causing a lot of damage to the invertebrate numbers including our only native species which is now protected...