Here's what's particularly interesting: level 5 seems impossible. Until you realize that the treasure chests can be moved in the same was as the fishy fish.
In level 8, it also seems impossible. Then you realize that you can destroy treasure chest by tapping on it twice.
Also, you must land exactly on your spot. It's possible to overshoot it, similar to Lunar Lockout.
What's very different: let's say you're hugging the left wall. You CANNOT get behind the fish and push it rightward. However some levels have purple plungers that will push your fish - but only as far as 1 square.
Big Negative: way too many ads pop up.
There are 24 levels. Of those, I've done all of them.