I can't tell what sex it is from the pictures. If it's like most other freshwater crayfish, the female will have a small lump on the second set of legs (from the front of the head). The males have a small lump on the bottom set of legs. The lump is where the legs attach to the body.
The following link shows where to look on Yabbies, which are an Australian freshwater crayfish, but they all get sexed the same way. In the video the guy counts up from the tail and the females have the lumps on the 3rd set from the tail, and the male has the lumps on the legs closest to the tail.
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Crayfish are best kept in tanks without fish. All freshwater crayfish are nocturnal predators and will try to catch and eat fish in the tank. Feeding the crayfish at night just after lights out will help reduce the chance of them killing fish during the night. However, there is no guarantee the crayfish won't go after fish after it has eaten the food.