This would really depend on what sort of fish you intend to house in your aquarium, as different freshwater fish have vastly different needs. Freshwater fish that are bred in aquariums generally haven't known their natural environment and don't much care if they are in a well-lit, planted tank with appropriate filtration, aeration and feeding.
Most aquarium books give guidelines on setting up aquariums to mimic particular environments, as well as stocking advice on fish that would have inhabited that sort of environment.