you can always tell if you are overfeeding when you water gets funked up and cloudy. when that happens to me (not very often) sometimes when my angels constantly beg for food i may overfeed and if i notice my waters a bit cloudy, i don't feed my tank for 2-3 days.. and it gets crystal clear. Remember its better to underfeed than to over feed. Im not to worried about the growth rate of my fish or breeding them, if you are trying to breed your supposed to feed more too i believe.
i usually feed flakes once a day, shrimp pellets every other day, Algae wafers every other day( shrimp pellets one day, algae wafers the next) Bloodworms every day to every other day (sometimes only a little) and fresh veggies i try to feed 2-3 times/week, but sometimes everyday depending on what i have. I buy a zucchini almost every week, but ive gone a week without the fresh veggies when i kept forgetting to pick up a zucchini.