Hey a nice simple addition! I like the controls, I had to look them up though, if you could include them at the start of the game (just use mouse scroll) this would have saved users from having to guess as they aren't obvious!
I like the art style, the gameplay is simple but hard, I got 8 fish, I tried short scrolls, long scrolls and found neither improved my performance, I wonder if I could increase my scroll speed in windows to cheat ;) hehe
I like the music in the background, nice and relaxing!