what is the difference between pigs and salmons?
which one is better to feed the world?
in food secutiry, we need to address the issue of "feed conversion rate"
some answers are here
When compared with terrestrial animals, fish are particularly efficient in converting feed into flesh. While the feed conversion rate for pigs is now around 2.5:1 and poultry at 1.8:1 and leader in the animal world, tilapia records 1.6:1, shrimp at 1.5:1 and salmon at 1.1:1. The latter is the most advanced and may soon achieve a 1:1 conversion rate!
"Why is it possible for fish to achieve these extraordinary conversion rates?" he posed rhetorically.
Fish live in a world where there's little effect of gravity and as a result expend no energy to fight gravity. Therefore there is no need to build massive bone structures to support their weight. In addition, fish are endothermic - meaning they need to expend no energy to warm their bodies.
"Everything they eat goes into motion and growth. Also they have high fecundity, meaning they have lots of offspring." Pigs might be able to achieve an impressive 27 piglets per year, but fish can produce 50,000 eggs twice a year with mortality rates of between two and three percent," he adds.