Crustaceans, such as crabs, provide a high quality protein and omega 3 fatty acids that provide potential health benefits. Crabs have commercial importance worldwide constituting one of the main fishing resources. For this reason, in the last 30 years, Crab aquaculture has been identified as an emerging aquaculture sector with significant potential. In conjunction with the growth of these industries, there was an increase in the study of the diseases. This book discusses the diseases and factors that cause diseases in crabs. It also discusses population ecology of mangrove crabs in Brazil; behavioural repertoire and substrate choice of the freshwater crabs; intracohort cannibalism of the mud crab; biodiversity of Venezuelan brachyuran crabs; alien crabs in the Mediterranean Sea; and the evolution of mangrove crabs distribution in the Atlantic coast of Cameroon.