If A⇒B and C⇒B then A⇒C and C⇒A, where B is "cute", A="all girls", C="all fish". But in these statements the implications are tacitly presumed to be reversible when, in fact, they aren't. A⇒B does not mean B⇒A or A⇔B.
If C is the set of all cute things then G, the set of all girls is a subset of C.
If F is the set of all fish then F is a subset of C. The relationships between the sets are shown in the diagram.
All girls are cute does not imply all cute things are girls. All fish are cute does not imply all cute things are fish. The word "are" is not used as an equality but to indicate a property. 1+1=2 and 2=1+1. Here the equals sign is used to indicate absolute equality. So one statement implies the other 1+1=2⇔2=1+1. Also 2+2=4 and 1+3=4 imply 2+2=1+3 and 1+3=2+2.