In a freshwater aquarium, provide at least water up to 40 to 50 gallons per lobster. Also, place plenty of rocks and plants. Temperature should be between 55 and 70 degrees Fahrenheit or 10 and 22 degrees Celsius, ideally with pH value 6.5-8.0
Place a male and a female freshwater lobster in the aquarium. Now it is really a difficult task to differentiate between male and female lobsters. The main difference between male and female lobsters is that the females have shorter claws than males and their claws are more rounded as compared to the male ones.
As you have placed both the lobsters, now you have to be patient. The process is a slow one. It is also best to keep both the lobsters in different aquariums. The male lobster should be introduced in the female lobster's aquarium and the mating process will start within one minute after the introduction of the male lobster. Usually the mating process is initiated by the male lobster; female lobsters do not initiate mating process. As the process starts, both the lobsters will clean each other. Now you watch closely. The process will continue for about half an hour, and when it is over, the male lobster can be removed from the female's aquarium.
After the mating process ends, the female lobster will carry the eggs in her abdominal parts, known as pleopods. The eggs have to be matured before they are extracted. The eggs will hatch in about 21 days or you can say, 3 to 4 weeks.
Lobsters are semi-aggressive in nature, and as an omnivorous, they can eat their own brood. So to prevent the parents to eat the broods, place them in a separate smaller aquarium. Try to keep the water of aquarium of newly born lobsters which are known as fry, as clean as possible. It is the time when fry will shed its shell and you should prevent from touching the fry as they are very fragile at this stage.
Image courtesy: aqua.org.il
As it shed its shell, leave the shell in the aquarium, as a part of its diet it will eat the shell. It will be a source of calcium which will harden the shell of newborns. As they grow larger they will regenerate the lost limbs.