The fish is always the moving vital mind making all kinds of formations.
There is a part of the nature which I have called the vital mind; the function of this mind is not to think and reason, to perceive, consider and find out or value things, for that is the function of the thinking mind proper, buddhi, — but to plan or dream or imagine what can be done. It makes formations for the future which the will can try to carry out if opportunity and circumstances become favourable or even it can work to make them favourable. In men of action this faculty is prominent and a leader of their nature; great men of action always have it in a very high measure. But even if one is not a man of action or practical realisation or if circumstances are not favourable or one can do only small and ordinary things, this vital mind is there. It acts on them on a small scale, or if it needs some sense of largeness, what it does very often is to plan in the void, knowing that it cannot realise its plans or else to imagine big things, stories, adventures, great doing in which oneself is the hero or the creator. What you describe as happening in you is the rush of this vital mind or imagination making its formations; its action is not peculiar to you but works pretty much in the same way in most people -- but in each according to his turn of fancy, interest, favourite ideas and desire.