Dog fish (Cartilaginous fish):
1.It belongs to phylum chordata,class pisces, and sub-class chondrichthyes.
2.Body streamlined and divisible into head, trunk and tail. Mouth ventral. They are marine cartilaginous fishes, e.g., Scoliodon.
Cat fish (Bony fish):
1.It belongs to phylum chordata,class pisces and sub-class osteichthyes.
2.It is a bony fish and its endoskeleton is made up bones e.g., Clarius (magur).