The goal does not change, it is always to bring the wheels to the same configuration as the original one. This set of challenges is called aquarium because all the fish-like colored shapes are kept intact. The difficulty level is going from rather easy to increasingly more difficult.
Original configuration
In case you get lost after making wrong moves, you can reset the two wheels to their starting positions using this button:
If you feel you are stalling here, then the link below might bring you some help.
Before you click be sure you've done your best and are ready to give up on this challenge.
If you are in a situation where you solved about the first half of the cases and for some reason can't make it with the last ones. Then chances are that you are doing your best to apply a strategy that was successful to solve the first cases, but whatever you do can't come to an end with the last cases.
If such is the case, then you must know that keeping on this path for another couple of centuries, will still not bring you to a solution. On the other hand you will get better chances if you go back to work and try to find out a different path. And finally the other way is to click on the link hereafter and find a solution to your issue.
Aquarium Rescue