The present disclosure relates to imaging for determination of crustacean physical attributes. An image of a shell of a live crustacean is captured and processed to determine a physical attribute of the live crustacean. In an embodiment a characteristic of a pattern indicative of moult stage of the live crustacean is detected, from the captured image. Multiple images may be used in some embodiments, including images of different types such as visible spectrum images, infrared spectrum images, and/or ultraviolet spectrum images.