Mangrove ecosystems are very important because of its many ecological and economic functions. It provides food, shelter, and protection to a myriad of organisms and maintains connectivity with other coastal ecosystems. It holds diverse forms of both floral and faunal associations, which are used by humans for different purposes. This review discusses the physiognomy, ethnobiology, composition of mangrove ecosystems with emphasis on associated fauna and mangrove crabs, fish production, and the human threats that can alter the stability of mangrove ecosystems. Different journal articles, books, manuals, and other online sources from both local and international sources were used to discuss the review. Mangrove ecosystems were found to be occurring in tropical and subtropical areas and are distributed horizontally in estuarine and vertically in intertidal zones due to a number of environmental and biotic factors. The ecosystem is composed of diverse associations of communities of both floral and faunal groups. Many of these associated fauna are benthic macroinvertebrates and fishes, a number of which are sourced as fish products. Fisheries are the topmost economic use of mangrove ecosystems. Fish products harvested include mud crabs, shrimps, mollusks, and fishes. The continued growth of human population and the industrialization of fishing exceeded our sustainable use of waters leading to the declining fish landings. Such event gave rise to aquaculture, which has become the main cause of diminishing mangrove ecosystems. Other human threats to mangrove ecosystems include mining, overexploitation for economic services, and urban development. Along with mangrove decline is the ecosystem’s susceptibility to climate change particularly on the rising sea level. This indicates a higher risk to flooding, tsunamis, cyclones, and storm surges. Hence, protection, conservation, rehabilitation and restoration of mangrove ecosystems, and its sustainable use are essential. Eco-friendly aquaculture must also be implemented.