i have seen some people on this site housing crayfish with larger fish. i'm considering adding a blue to my 125 gal with two 4 inch oscars, one arowana of 6 inches a pleco of about 8 inches and one senegal bichir of about 6 inches. is it safe for the crayfish? i have to assume that some large predatory fish might attempt to eat a crayfish. your thoughts are appreciated.