That's true for carnivorous fish like salmon, but an omnivore like catfish will eat pellets made of grain and produce meat at a 2 to 1 ratio, on par with poultr

That's true for carnivorous fish like salmon, but an omnivore like catfish will eat pellets made of grain and produce meat at a 2 to 1 ratio, on par with poultry. It's a matter of the consumer being aware of the difference and being able to trust the labeling (and the implied farming practices).