iv been reading alot on here and thought id share a little from my experience , i have a crawfish i found on the bank of the ohio river back in january of this year it was black in color cold and barely moving so i brought it home and put it in my 55 gallon fish tank , theres 3 fish in there and they all seem to get along well together , since he has been in there he has shed out his skin 3 times and changed colors twice he is now greenish grey was red and before that black . this crawfish lives at the bottom of the tank he never comes to the surface crawfish are just that , fish . they dont require air to breathe they can do so as fish do . i feed him shrimp pellets and he seems to be fine with them . he has a big rock in the back corner to hide under i think he likes it , but i may get him a freind soon to see if they will mate , i have another tank i dont use that might become their knew home . id post a pic but my bro has my camera .