Oh yes, fish lie. Ours lie all the time. 'I have not been fed; in fact I have never been fed in my life'. "You were fed ten minutes ago!" Nothing wrong with their memories.
I feed them, then my wife enters the room and they wait until I leave before doing the "butt wiggle dance" so she feels sorry for them and feeds them - then tells me off for neglecting them. Indeed, they know, and are very clever and know how to manipulate us to their benefit.
Ah goldfish, simpler days! If I feed the tanks and only get partially wet and not bitten I consider it a good day. Putting a hand in the water for maintenence is an adrenaline sport!