Really cool demo I had fun playing it, the only issue I had was that It wasn't always clear what I was supposed to do, (especially next to the waterfall It would help maybe making that sing indicator a bit more noticeable, I know there were these fish pointing up but I only noticed them after I got up there , I would change fish color to stand out a bit more from the water)
Maybe I would also suggest to move camera a bit up so player sees more ahead .
Other than that keep it up and good luck on finishing the game :)