Using the prototype model, how would one form a concept of a fish?

The Prototype Model is a theory of graded categorization developed cognitivists such as Rosch (1970),  Driven and Taylor (1988) which states that a concept is represented by a prototypical element. Thus, there are certain characteristics that frequently co-occur and lead to the definition of a certain category. It is worth mentioning, that certain members of a category are prototypical and they are not all equal. For example, if we think about the concept furniture, table is more frequently cited than counter or desk.  

If we are asked about the concept of water animals for example, we will probably think of fish (they all live in the water, they have fins, they can swim, they can be of different shapes and sizes). Going deeper, if we are asked about the concept of fish, we would probably think about a little, two-fin, orange one and not, at least at first, about a shark or a whale for example, though this depends on our experience.  

can you explain it better