This feels very basic. It's pleasant and calming but there isn't a lot here. I see that you used a lot of the fish model and it looks like you might've used the jewels as rocks for the cavern. I think all of that works but there doesn't really seem to be a reason to anything I'm doing. Once I've played this for about 5 seconds I've gotten the entire experience.
I think it would've been more interesting if you forced yourself to use more of the included assets for the game. The bizarre nature of the assets force you to create strange things but it feels like you chose one, the fish, and just created a game which only really needed that once asset.
Additionally, the fact that there is an invisible ceiling is slightly strange to me and the fact that the rocks are blue doesn't make this feel like a polished experience. I assume you made the blue to simulate being underwater but I think adding a thick blue fog on the whole game might've been better.