At least some of them are. Among other species, farmed fish are being fed sardines, mackerel, and a tasty fish that doesn't seem to have an English translation

At least some of them are. Among other species, farmed fish are being fed sardines, mackerel, and a tasty fish that doesn't seem to have an English translation (it's "jurel" in Spanish). Sources (sorry, in Spanish... it's rather difficult to find info about fish in English if you're Spanish, because we don't eat the same species, we don't even name the same species, and when we do, there is not necessarily an one-to-one map between Spanish and English names). https://www.elconfidencial.com/tecnologia/ciencia/2019-10-17/peces-comida-harina-aceite-ecosistema-transparencia_2287371/ https://www.elconfidencial.com/tecnologia/ciencia/2019-10-17... https://www.elmundo.es/elmundo/2012/04/24/natura/1335258947.html https://www.elmundo.es/elmundo/2012/04/24/natura/1335258947.... Personally I strongly prefer the taste of some of these species they feed farmed fish than that of the farmed fish themselves.