Great demo! I love the artstyle and the music, they create a very cozy chill atmosphere that fits the game very well! Also I really like the idea of upgrading the aquarium with decorations. One thing i found a little annoying was how fast the filter was moving when it is upgraded to level 8 or more, maybe you could indicate a higher level filter with a longer filter or maybe a different color later. But overall it was very fun to play! I look forward to seeing more updates in the future :)