Hey Benji,

I am not a pro but, based on the inputs I have read here on the forum, I can offer this.

1) The crayfish will not bother swimmers
2) Choose a crayfish variety, such as papershell, that will not burrow.
3) Without predators, crayfish will multiply and can remove most all the vegetation in the pond. You have predators from your post that will love crayfish so this is probably not a concern for you.

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