There is something circular about the idea of catching fish to use as feed for farmed fish, livestock, poultry and our pets. And with about one third of the global fish catch going in this direction, most of it destined for aquaculture, you might well ask whether growing the farmed fish to put in your supermarket has deprived a hungry or malnourished person of food.

The idea that fish is a healthy diet choice is widespread, but fish differ in the benefits they offer, with implications for how we help the malnourished.