DIY Automatic Fish Feeder. Automatic Fish Feeder in Action. Finally I am done with my Automatic Fish Feeder. Its simple and cost less than Rs 300. Basic Principle: A cylindrical drum is attached to the hour needle of an electronic alarm clock. The Drum completes 2 rotations in 24 hours. A small hole in the drum with a straw, ensures that food is dispensed every 12 hours. The cut made in the straw, determines how much food is dispensed each time. Here are the things you need: An Electronic Analog Alarm Clock like Orpat Alarm clock. A small plastic cylindrical light weight container (preferably transparent). I took a small container in which you get camphor balls used in religious rituals (Pooja). A small plastic straw/pipe. A pipe used in Aquaguard water purifier is fine. Its diameter is around 7-8 mm. The operation is self explanatory. If you are still confused then you can refer the following sites. http://www.instructables.com/id/Cheap-automatic-aquarium-feeder-on-the-go/ http://bahatanju.pbworks.com/w/page/9065926/My%20Hacks A few tips: Make the hole for the straw on the drum, a bit smaller so that you do not have to use a glue to hold it in place. You can then create 2-3 small straw with different cut size to dispense different amount of food. Whenever you have less fishes in tank you can use the straw having a smaller cut. Do not load the drum full. Keep it half filled otherwise all the pellets may drop out in one go. Try to get the lightest cylindrical drum so that you can fill more food pellets. Every clock needle motor has a threshold of how much load it can take. So do not over load the clock with a heavy drum filled with food pellets. You can use mustard seed for testing your DIY Automatic Fish Feeder.