Table 2. Top vertebrates in global aquaculture by number of individuals and environment (freshwater versus marine).
Although there is a modest body of welfare literature for some of these species (five or more welfare publications), several species have very few or no publications about their welfare, or their species is unknown. In the FAO data, nei stands for “not elsewhere included.” N/A, not applicable.
| FAO listing | Species | Individuals (billions) | Environment | Welfare |
| Nile tilapia | Oreochromis niloticus | 7–16 | Freshwater | 5+ welfare |
| Carassius nei | Carassius spp. | 5–11 | Freshwater | Species unknown |
| Silver carp | Hypophthalmichthys molitrix | 4–10 | Freshwater | No welfare |
| Grass carp | Ctenopharyngodon idellus | 4–8 | Freshwater | Little welfare |
| Common carp | Cyprinus carpio | 3–8 | Freshwater | 5+ welfare |
| Atlantic salmon | Salmo salar | 2–4 | Marine | 5+ welfare |
| Marine fishes nei | N/A | 1–2 | Marine | Species unknown |
| Gilthead seabream | Sparus aurata | 0–1 | Marine | 5+ welfare |
| Large yellow croaker | Larimichthys croceus | 0–1 | Marine | No welfare |
| European seabass | Dicentrarchus labrax | 0–1 | Marine | 5+ welfare |