As for the crayfish I can probably catch a hundred or so of those in the local South Branch of the Potomac watershed in one or two nights thereby eliminating any issue of non native species.
Many species of crayfish found in moving waters are not going to do well in a pond. You may be better off trying a local pond or lake for your crayfish trapping. Then you'll know the species you catch are suited to a still water life.
