Very cute animation!

You got my vote, I like it a lot!

Thanks so much for your advice. It really helps a new pixel artist like me.

Nice little mermaid. I think the hair movement is a bit much for such a small sprite, but it might work if you slow it down. But the animation works well overall! If you tint all the colors a little greener it'll look more like she's inside the bottle. You could also have a bubble or two rise in front of her.

Also, I believe a transparent (or detailed) background is required according to submission rules.

Cute!