Ages ago, when the seas still shimmered underneath the shining sun, Fish had no choice but to cower in his cove and concede the ocean to Cat. For you see, in those times, Cat was not at all afraid of the water; in fact, from dawn to dusk, she would wade into the waves, hoping to finally find the ever-elusive Fish. She would swim for hours upon hours, braving the tremendous tides until the skies above glittered with the first twinkles of starlight. Then, and only then, would she emerge to sleep on the shore, waiting for the morning rays to peek over the horizon and begin her routine anew.
This proved to be a problem for Fish; as much as he wished to explore the ocean in which he called home, he could not do so unless Cat surrendered her pursuit during the day.
Now, you may ask: why does Fish not leave his cove at night, when Cat is sound asleep atop the sand? Well, truth be told, Fish did attempt to do so, once. But, much to his shock, he discovered that darkness transformed the sea into a far more dangerous place than he believed it could be. Creatures of every shape and size emerged from their own caverns and chased after Fish, snapping their fearsome jaws at his flittering tail until slivers of sunlight drove them back into their dwellings.
From then on, Fish refused to leave his cove unless the sea was illuminated with sunshine— A fact that Cat took full advantage of, much to his dismay. Hence why Fish had resigned himself to this miserable existence, wasting his days wondering if Cat would ever tire of her hunt for him and leave the water for good. Alas, Cat was too stubborn, and so the chase continued.