u/Euxkan

My son had one gold fish for while and it was very active alone. Recently we added one extra and what I noticed is that both stay at the bottom of the tank like they are in sleep most of the time. They are do not actively swim around.

Should I be worried? Conditions: 30 gallon tank. Recently had a 50% water change. Feed sink type foods. API water quality test shows both Amonia and Nitrate in safe range. I am concerned.