Like others have said, most crayfish are carnivores or omnivores and most are usually nocturnal and would possibly/probably prey on other inhabitants... mainly any other bottom dwellers or fish that sleep near the bottom. If your fish are mostly mid-level and top-level fish and are fast swimmers, they may elude predation although an occasional fish may go missing. The shrimps might be the first to go since they share the same habitat and would not be able to defend against the strong pincher of the crayfish.
There are a couple of different species of crayfish that have a blue variant. What area of the world do you live in? Did you buy the crayfish? You might want to ask at the store for the exact species (scientific name) so you can do more research on suitable habitat and tank mates.