Ribeirão Grande is a richly biodiverse watershed located in the eastern portion of the Serra da Mantiqueira mountain range in Minas Gerais, Brazil. This stream system stands out among neighboring watersheds for its exceptional fish diversity, harboring the highest species richness of any watershed studied in the region — a remarkable 30 fish species recorded across its drainage. The watershed encompasses both slope (encosta) and piedmont (pediplano) segments, each offering distinct habitat characteristics and fish communities. The transition from the steeper upper reaches down to the broader piedmont zones creates a variety of aquatic environments that support a wide range of species, making Ribeirão Grande a genuinely compelling destination for anglers interested in native Brazilian freshwater fish.