did you know that feeding your fish even once per day is excessive compared to their natural feeding schedule?
in the wild, they spend all their time finding food rather then actually eating it. you eliminate this factor, and they don't feel they need to forage/hunt and do exactly as nature intended: nothing.
thats why if you go diving or swimming in lakes/oceans it feels more majestic because fish are always swimming around or picking at things. all a wild animal has to look forward to in life is finding food and mating. seriously!
when you go to a professional aquarium, you wonder why their fish look so much better than yours? (generally speaking). they simply have so much fish that not every fish eats, every time. which always leaves room for activity.
what you can do is feed every other day. fish can also go a month without food (the more carnivorous the fish is, the longer it can go). where as leaf-eating fish MUST always eat. (99% of the fish sold at lfs are carnivorous. flakes are made of animal product. all the way up to pellets unless labeled otherwise).