For this project, you will need to keep the flakes of fish food suspended over the water so they do not become soggy or accidentally fall into the water. Use a timer-switch to determine what time of day the flakes will be dropped into the water by a dispenser attached to the timer. Also, make sure the dispenser does not simply unload too much food into the water by filling it up only until a certain point and keeping the dispenser open only for a second or two.
An automatic system set on a timer switch can be used to close and open blinds during certain parts of the day. This is a great project to use in Mechatronics. This project can also be used to simply slant the blinds throughout the day so only a certain amount of sunlight penetrates.
Use robotics to make your Halloween costume come to life. Animate the face of the costume so it spits out "blood" or "bile" by connecting a spray mechanism to a remote control you can activate. You can also make your costume animate in the arms or legs in some way by using Mechatronics. This shows how Mechatronics can be used for recreation rather than just for practical projects.
Make a remote control car that can follow a wall by attaching an IR sensor to the side of a the car. You will also need to replace the car's motor with a servo motor, which can better interact with the IR sensor. The IR sensor reads the distance to the wall and follows the line of the wall, commanding the motor to take the car in the direction the wall goes.