To care for live crayfish, also commonly called crawfish, provide them with the appropriate temperature of clean water in a large enough tank. Give them hiding places and a substrate they can burrow in. Feed them a diet of shrimp pellets supplemented with plants.
Most crayfish varieties live in cold water, but there are some tropical varieties that need heated water. A filter is also very important for their survival, so make sure you have one running. At least 25 to 50 percent of the water in the tank should be changed every week because crayfish are messy eaters and like to hide food stashes, which can reduce water quality. Although it may not be necessary for their survival, adding liquid calcium to the water can strengthen their shells. Providing calcium-rich vegetables, such as spinach and peas, also helps keep them healthy.
A single crayfish can be kept in a small tank, but multiple crayfish need to be kept in at least a 20-gallon tank with multiple hiding places or they may eat each other. Crayfish may also eat fish that are kept in the tank, so it is best to keep them separated. Crayfish shed their shells periodically and go into hiding while they grow new ones, so they must not be disturbed during this time.