First, it seems like he cannot move around without water inside his body tank.
He wanders around to collect even a tiny drop of water.
However, when he reaches out to an object filled with water and breaks it to fill the water into his tank, he realizes that there is a fish in it.
After that, he actually realizes that he's underwater.
I think the message is that we shouldn't be too greedy to get something but to look around and see what you already have and accept it.
