This appears to be a larger version of the minigame advertisement from the tablet game Fishdom.
It works for the most part, although maybe some of the corners where fluid is accumulated could be a rounded or minor slope, there is a level where you literally win on the last available drop.
Since this is basically a clone of another game, I think you could take the chance to add something special to it. The first thing that comes to mind would be challenges that have either multiple enemies or multiple fish that need to be saved. Some loose plot would seem nice. Right now the levels all feel nearly identical except for a few. I think integrating in some plot could really help alleviate this.