What is considered overfeeding?

I have a african cichlid tank with 20 fish. they are all still small with the biggest being around 2.5" and I have been feeding them 3 times a day and I throw in a hearty amount of flake food yet they always seem hungry. I can walk into the room 5 minutes after feeding them and they all come up to the top of the tank in a frenzy for more food. I have also had problems with cloudy water yet I do a weekly 40% water change. should I cut down on their feeding to twice a day?