The main features of Pisces are:
(i) They are exclusively water living animals and include the fishes.
(ii) Their skin is covered with scales/plates.
(iii) They obtain oxygen dissolved in water by using gills.
(iv) Their body is streamlined, and a muscular tail is used for movement.
(v) They are cold-blooded and their hearts have only two chambers.
(vi) They lay eggs.
(vii) Some fish varieties have their skeletons made of both bone and cartilage, such as Anabas, Sea horse, Rohu, and some have their skeletons made entirely of bone, e.g., Torpedo fish and Sting ray (Trygon).
