Cute but fragile: Rainbow fish
Each site has its own particularities. Although data on rainfall in the Ivondro catchment area has been available since 1901, knowledge of the river’s ecosystem has yet to be fully developed. The installation of a project like Volobe amont will provide a better understanding of the aquatic environment thanks to the various biological studies carried out by its technical partners over the last few years.
Bedotia madagascariensis (Regan, 1903), known by its Malagasy vernacular name ‘Zono’ or ‘arc en ciel’ fish in French, is found in central-eastern Madagascar (Kiener, 1903). This emblematic Malagasy ichthyofaunal species is found along the Pangalana canal between the Ivoloina river and the Manambolo basin south of Vatomandry (Loiselle and Rodriguez, 2007), including the Ivondro river. This species shows marked sexual dimorphism in morphology and coloration, ranging from red to golden yellow and black (Loiselle et Rodriguez, 2007).
Bedotia madagascariensis is more commonly found in shaded streams in the eastern coastal plain. However, it can be found in large rivers and lotic sections (Loiselle and Rodriguez, 2007). It can be found in freshwater, as in the case of the Ivondro tributaries, to hard, brackish water near the ocean.
Bedotia madagascariensis is threatened by predation by the snakehead fish or Channa maculata, apart from other natural predators such as Paratilapia, Kuhlia, Mesopristes elongatus, Glossogobius giuris and eels. Similarly, this beauty of eastern rivers is threatened by overfishing, especially in recent decades as a result of the use of mosquito nets.Many thanks to Biotope Madagascar for its technical support for the Volobe upstream hydroelectric development project.