There are approximately 175 species of freshwater fish that live in Madagascar including the endemic species, the native species, and the introduced species, the list can be found at the following website: http://fish.mongabay.com/data/Madagascar.htm. Some of those introduced species have threatened the endemic species and that tied with the conversion of native vegetation to rice paddies and erosion resulting from deforestation makes Madagascar’s fish species some of the most threatened on the entire planet. An interesting phenomenon is the finding of the Mal
agasy Crayfish, there are so far six endemic crayfish species found in Madagascar. There are no crayfish in either Africa or India, meaning that the Malagasy Crayfish have a much older origin possibly reaching to South American origins like the snakes.1 Fish that are found the Malagasy region’s crater lakes are considered “living fossils” because they belong to the most primitive of catfish, herrings, cichlids, killies, silversides, and their allied species.2
1 http://www.wildmadagascar.org
2http://www.wcs.org/where-we-work/africa/madagascar.aspx/freshwaterfishconservation