Crawfish are not difficult to keep in an aquarium, and they're interesting pets to watch. They can be purchased from many pet stores or caught in their natural habitat. Also known as crayfish, there are many varieties to choose from, such as the blue crayfish, Louisiana crayfish and dwarf crayfish.
Provide at least a 10-gallon tank for a crawfish, and make sure to add a tight-fitting lid as they will explore every inch and could escape. Place sand or smooth gravel in the bottom of the tank, and add plenty of plants and decorations to provide hiding places. Use an aquarium pump to help keep the water clean. Every two weeks, remove 10 to 15 percent of the water from the tank and replace it with fresh, chlorine-free water.
Provide a pellet-form fish food that will sink to the bottom of the tank daily. Supplement with small pieces of vegetables and fresh meats. The more variety provided for meals, the healthier the crawfish will be. Be sure to provide plenty of calcium-rich foods such as spinach and zucchini to aid in the molting process as the crawfish grows. Calcium drops can also be added to the water. Remove any uneaten food after 20 minutes to avoid bacteria in the tank.
Although it's very difficult to correctly sex a crawfish, if you have several in a tank there is a chance they will breed -- assuming they have the right food and good health. The male deposits a sperm packet on the belly of the female. The female then expresses the eggs through the sperm packet and holds them on her tail until they're ready to hatch. The length of the incubation period varies depending on water temperature and type of crawfish. The fry will be very tiny, yet fully formed crawfish and will feed on anything they find in the bottom of the tank. Small bits of boiled lettuce are a good food for crawfish fry.
Crawfish are hardy and not susceptible to illnesses with good care. Avoid cleaning the tank or handling a crawfish after they've molted as they are extremely sensitive at that time. Ensure there are plenty of places to hide during molting to keep them safe from other crawfish. Crawfish may lose limbs during breeding or if involved in a fight with another crawfish. These limbs will regrow after several moltings.