need identification help with a crayfish

[dragun84]

I have a rather now large crayfish it has molted four times now and has changed color three times and is now a strange bluish purple or vise versa anyway I'm have tried very hard to find what species it is so I know roundabout how much bigger it shall get I will also.post a pic of it so there is a better idea of its coloring and deatails

[Jozle]

Looks like a blue lobster that has change in colours due to water parameters? Not sure, but mine was blue when I got him many moons ago and then he turned bluish with violet coloured before he got killed.

[Totenkampf]

i know that diet can affect the shell color some, i'm no help on the ID tho

[allysangels]

where did you get it? what do you feed?