I have seen retenone applications with dead crayfish as a result as well. Not sure if the retenone did it, but they weren't dead before, but after the application they were...
I think I read somewhere that rotenone prevents red blood cells from carrying oxygen. Not sure crawfish even have red blood cells. Sure haven't ever seen one bleed!
Maybe rotenone kills them, but is not effective at controlling them because it doesn't get down into their burrows. (?)
