How large are the fish? Maybe they are just enjoying hiding in the rocks.
How did you cycle the tank? A reading of zero nitrate is usually a sign the tank is not cycled. Which type and brand of test kit are you using?
Any chance you can post a pic of the tank?
How did you cycle the tank? A reading of zero nitrate is usually a sign the tank is not cycled. Which type and brand of test kit are you using?
Any chance you can post a pic of the tank?