If this is just a problem about feeding... (your fish are okay)
When did this start? You just simply low down the food. Cause "Underfeeding is always better than overfeeding" Fish just won't starve to death in several days. We can never know what's "much" and how's "enough" for the first time you feed your fish.
The ideal time to feed your fish is in the morning or about 6 PM. Don't feed them at night unless you have some nocurnal creatures. And try many types of food so that you'll find what will be the best. Many will blend themselves to feed on what they don't want but it's better for you to pick up their favs. Try some variety of food and some flakes too!
Hope that helps