- [Narrator] She's on the lookout for an eligible partner.

The bigger, the better.

Our spy fits the bill.

Waving her fin like a flag is another good sign.

Our spy waves back.

But this is where it all goes wrong.

There are plenty more males to choose from.

Spy Mudskipper has serious competition (mud squelches) and their flag waving is far more seductive.

But to really impress, flagging alone is not enough.

He must show what else he can do.

(mud squelches) As emotions soar, it's now a competition.

(mud squelches) There's one yet to take its turn.

(mud squelching) Hardly a serious contender.

She's after the one that leaps the highest.

(mud squelching) (water splashing) She approaches the two best contestants.

Our spy is cast aside.

There can only be one winner.

To decide, they must fight it out among themselves.

(mud squelching) (water splashing) The female awaits the result.

Finally, the loser is driven away.

She has her champion.