Cartilaginous FishExamples include ray, dogﬁsh, shark.
Oil-Rich ﬁshare so called because the oils are distributedthroughout the ﬂesh of the ﬁsh. Mackerel, herring,salmon and trout are examples.
Finﬁsh are occasionally classiﬁed in a diﬀerent way—according to where they swim in the sea. Demersal ﬁsh are those which live on or near theseabed. Round and ﬂat whiteﬁsh fall into this categoryPelagic ﬁsh swim in mid-waters or near the surface.Examples are oil-rich ﬁsh such as mackerel, herring andtuna.