[shaneofalltrad]

This seems to be a very generalized statement when there is a lot of variation to consider. There are 33,000 fish species, some being specialized feeders of algae, to 100% live fish, all designed for processing each food differently. Are you speaking on a specific fish that is commonly "farmed"? I could see Salmon needing this 20kg and not even contain the quality fats they get in the wild, resulting in a lower quality food on top of being more impactful to the environment.