No, nobody here took your comments as argumentative... after all, you were only adding your .02 just like the rest of us. 
To sum up what's been said, and to capitalize on the key points, fish that are domesticated should ideally be fed dead food, that is, any food which isn't swimming around. You can find a wide variety now-a-days and its really easy to switch a fish's diet because of the wide variety of non-live foods out there.
But yes, the more wild the fish (and esp if they are carnivorous) the harder it will be to try to change what it is they eat.
To sum up what's been said, and to capitalize on the key points, fish that are domesticated should ideally be fed dead food, that is, any food which isn't swimming around. You can find a wide variety now-a-days and its really easy to switch a fish's diet because of the wide variety of non-live foods out there.
But yes, the more wild the fish (and esp if they are carnivorous) the harder it will be to try to change what it is they eat.
