This is a model I recently made, it was rendered in Cycles. Post-processing was done in Gimp. Enjoy 
Full resolution: http://flitsart.deviantart.com/art/Crayfish-updated-version-484952745
Nice! Looks pretty real. I’d give it some more red color to help it “pop” out of the scene more.
I really like it! Very realistic! 
Just noticed the baby one
This is pretty awesome. Almost didn’t notice the baby there lol
Pretty cool but the water needs more murk to it. Use volumes/particles?
Thanks for all the feedback!
@Kemmler, I didn’t use any volumetrics or particles. The image was based on a photo of a clean aquarium, but it would be a nice touch.