Originally Posted by DigitalAquarium
How many fish in your freshwater aquarium?
If we are speaking about real fish,in real aquariums,
Much depends on the size of the aquarium,types of fish,filtration, and amount of foods offered.
In general, I try to keep nitrate levels around 20 ppm according to API Freshwater Master test kit.
If levels exceed this between weekly water change, then I have too many fish, or I am feeding too much,or I don't have enough filtration,or I need to do larger more frequent water changes.
Those who find themselves performing twice weekly water changes or more,, in order to maintain water quality, seldom stay in the hobby long despite their problems being largely self inflicted.