Here is a short fish tank animation that I made in blender and edited together using Final Cut. This is my first animation so its not the best but what do you think for this being my first animation.
Enjoy. 
Add some more detail to the static surroundings. You’re mainly really only animating a small portion, so if you add some detail to the tank, or surroundings, you won’t be in for much more work. Rendering will take longer, but it would definitely add to the scene, in my opinion.
Also, the sound… seems out of place. There’s no trickling or pouring water visible, and it sounds a bit high pitch for a tank, anyhow.
A good start.