Red Fish, Red Fish, Red Fish, Red Fish

But really, how do they tell who is who? It doesn't help that their memory's like half a second long, because not only can't they tell who they're looking for by, um, looking, but they end up asking the same fish over and over and over again.

Are you my father?

Are you my father?

Are you my father?

Are you my father?

Of course, what's the reply going to be? With a half-second memory, he's just got to guess at the first half of the question.

Green.

Short.

Two fins and an ugly nose.

A relationship based on the younger of the two being the spawn (we are fish, y'know) of the elder, whom happens to be of the male persuasion. The 'father' is the definition of the elder in such a relationship.