Great use of the exchange theme! Combining health and ammo into one bi-directional stat, and having to balance it from getting too far on either end is a brilliant idea! The bullet hell patterns are also quite well designed. I like the tongue-in-cheek humor, which definitely helps lampshade the chaotic art style.
I would recommend working to balance the different weapons a little better. The first weapon doesn't quite shoot fast enough to allow you to empty water when you are nearing too wet, so I found myself just using the second weapon. And I think a checkpoint system, so that you don't have to replay the entire level if you lost to a later boss, would lead to less frustration. But overall, nice work.