The goldfish (Carassius auratus) is a freshwater fish in the family Cyprinidae of order Cypriniformes. It is one of the most commonly kept aquarium fish. A relatively small member of the carp family (which also includes the Prussian carp and the crucian carp), the goldfish is native to east Asia. It was first selectively bred in China more than a thousand years ago, and several distinct breeds have since been developed. Goldfish breeds vary greatly in size, body shape, fin configuration and colouration (various combinations of white, yellow, orange, red, brown, and black are known).
Mechanical digestion is the physical breaking down of food particles into smaller food particles to increase surface area for chemical digestion. Chemical digestion is the use of enzymes to break down polymers into monomers (through the breaking of chemical bonds)
Polymers are classified by the characteristics of the reactions by which they are formed. If all atoms in the monomers are incorporated into the polymer, the polymer is called an addition polymer.If some of the atoms of the monomers are released into small molecules, such as water, the polymer is called a condensation polymer.Most addition polymers are made from monomers containing a double bond between carbon atoms. Such monomers are called olefins, and most commercial addition polymers are polyolefins.olymers are classified by the characteristics of the reactions by which they are formed. If all atoms in the monomers are incorporated into the polymer, the polymer is called an addition polymer.