people use those leaves to breed fish lower ph and to create blackwater or use the leaves for shrimp tanks as the shrimp eats it as they decompose. very beneficial. the amazon rivers are loaded with leafs on the bottom creating a leafy substrate. i often put a a load of indian almond leaves in my altum tank to create that amazon biotope. just gets nasty when they start breaking down. but the first couple of weeks i like the look of it.