How long can African and South American lungfish survive without food or water during estivation?

African and South American lungfishes are capable of surviving without food or water for extended periods—lasting months or even years—by entering a state of estivation during droughts.12

During this period of dormancy, the fish's metabolism, respiration, and heart rate drop to very low levels, which allows them to remain viable until water returns to their environment. Specifically, African lungfishes have been kept alive in an induced state of estivation for more than two years. While both types of lungfish utilize this survival strategy, African lungfishes typically burrow into the mud and encase themselves in a hardened mucous sheath, whereas South American lungfishes burrow into the mud but do not form a protective sheath.12