African penguins feed mainly on small pelagic fish (fish which swim on the upper layers of the open ocean) like pilchards, anchovies, horse mackerel and herrings. Competition with commercial fishing has forced them to adapt their diet. They now also eat squid and small crustaceans as well. Since penguins are capable of diving considerable depths, up to 35 m, remaining under water for 1.5 minutes, they can reach fish that other birds cannot.