Here is a smart fish feeder that allows for 14 positions with fish food. It gives just the right amount of food to your fish while on vacation. It is designed for pellets or other hard fish foods, not flakes. An Arduino Nano fits perfectly in the box, and there's also room for a Stepper motor with control board. I have programmed my Arduino to feed once a day, but this can easily be changed. I've included files for two different sizes. (Small is very small). The box and lid are the same for both sizes.

You need an Arduino Nano, stepper motor, stepper board, USB cable and power supply.

Use glue to attach the plate to the stepper motor. The turntable can also be glued, but make sure it can still rotate!

Note that an Arduino without a clock module will not be entirely accurate, but I believe it is good enough for fish feeding:)

Thanks to @trevor_DIY for designing the turntable! https://www.instructables.com/id/Betta-Fish-Feeder/

Also thanks to @superwoodle for inspiration for the motor cover part. https://www.thingiverse.com/thing:1215081