Last week, during Chinese New Year, I had to visit my hometown in Malacca for 5 days. Feeling worried that my fish will starve (perhaps even die) during the holidays, I quickly made a simple on-demand fish feeder out of materials available in my house before I begin my trip. The design is based on several DIY videos I found on youtube and some aquaculture PDF files that can be googled.
Though my design was based on the commonly used pendulum demand fish feeder, the food release mechanism works differently. The usual design requires the pendulum rod to be extended below the surface of the water so that the fish can activate the food release mechanism by bumping the rod. The problem is that my rod is made from iron and is slightly galvanized. Since I cant have the rod touching the water, I tied a string to the end of the rod and attached a ball of cotton rope at the bottom end of the string which floats on the surface acting as bait. When a fish bites and pulls the bait, the whole feeder shakes, releasing some pellets in to the water. Once the feeder was set up, I left my house with my fingers crossed in hopes that my tilapia will soon learn how to use it.
When I returned home, 5 days later, I found the feeder empty. The fish seemed happy, but I wasnt sure if the fish had learned how to use it yet. I refilled the feeder and stood in front of the tank for 30 minutes to see how the fish "use" it. Most fish just nibble or "kiss" the bait but occasionally a clever fish (perhaps just hungry for a bite) will pull and jerk it hard enough to release enough pellets to feed several fish. The feeder works!
The way my feeder works is by taking advantage of tilapias feeding behavior. When they feel hungry, they will start nibbling on anything they can find. The ball of white cotton rope with its hairy cotton strands looks attractive (at least to me) to them. Pulling the bait hard will shake the feeder which releases pellets in to the water where the fish can snack on. When the tilapias are full, they are less likely to nibble the bait. This way, feeding times will be much more regular which I hope will increase their growth rate and also provide less stress to the filtration system.
Hopper made out of mineral water bottle.
The disc is made out of a piece of thick paper with a bottle cap below it secured by rubber band.
Bait made out of a white cotton rope.
As usual, I will also include several photos of the plants...
Plants
Tomato (12" tall).
Bok Choy seems to be having iron deficiency.
Red Okra having problems standing upright due to the recent rain.
Roselle cuttings at the left and flowering kang kong plant at the right.
