Who is talking about mud ? Have a look :
amazon biotope tank no mud :
In most rivers and streams there is sand or rock on the bottom. When water is flowing it washes the sediment/ mud away and leaves a clean substrate. However, when the water is not flowing during the dry season, mud settles in areas and the bottom gets a thick layer of soft black/ grey mud over the substrate. When it rains, the water starts flowing again and washes the mud away.oh in some of their natural habitats i saw there was a lot of mud and rotting stuff
maybe it was just rotting stuff on sand![]()