From

Living a Buddhist Life: Vegetarianism by Bodhipaksa

Fish are the only commonly eaten animals living an entirely natural life (except for farmed fish). However, their death through suffocation when they are taken from the water must be deeply unpleasant. Fish farming causes serious pollution, not least because of the heavy metals used in anti-fouling paints used to prevent molluscs and seaweed colonizing the fishes’ cages. We have to remember that eating fish also puts us into competition with fish-eating wildlife. Part of the true price of fish is the culling programmes carried out on wild animals like seals and birds of prey to make sure there are enough fish for human consumption. Vast numbers of the fish caught in nets are not used for human consumption. The fishing industry call them ‘trash’, and dumps their corpses at sea. ‘Trash’ can constitute as much as half of a catch. An additional indicator of our lack of regard for both fish and land animals is that 40 to 50 per cent of the world’s fish catch is fed to farm animals - most of which are naturally vegetarian.