Very relaxing - zen-like game. I like your sounds - they are soothing. I had fun unlocking the different types of fish.
1. For parts the game was playing itself, because matches were coming in. Perhaps find a way to ensure that doesn't happen.
2. Some match 3 games will match all the matching blocks, you're only matching in straight lines. That's okay, but I would say so in the instructions, so people know it's a feature not a bug. (Maybe it is there, I didn't look for that type of info.)
3. Maybe over time you can add some special blocks that you unlock by matching next to them, to give the game more strategy.