Earthan Group - Paul Van der Werf

DIY Demand Fish Feeder

Ever wanted to go away for a few days and not worry about the neighbor feeding your fish or your fish going hungry?  Here is the thing.   This is a simple DIY fish demand feeder from some easy to get items.  Before we get started I would like to make a few points about feeding and possibly a few risks of using this method that will be of use to you.

These DIY demand fish feeders are great for most species of fish, however there are always going to be a few that are “dumber” than the others, so they do not take to it so well or as fast. This is where some perseverance will be needed while training the fish to accept taking food from this scary thing hanging above them. If the fish do not take to it after several weeks, you will want to upgrade to programmable shaker type feeders or find an alternate way of getting feed to your fish.  A belt feeder would be my choice.

There is always a risk of over feeding when using automatic feeders, especially demand feeders.   Some species of fish (gold-fish) will gorge on the feed until their guts pop out the back-end,  so this may not be suitable for them.

Others such as large juvenile barramundi will only need one feed a day, as most carnivores do,  so grazing all day may not be the best for them.  Not to say you cannot use them for that week-end away. Young, small fish (< 250 grams) and omnivores tend to need multiple feeds, (some up to 7 or 8 times a day) or prefer to “graze” throughout the day. This DIY demand fish feeder is ideal for them. They are very handy when you are away for a few days for most fish species.

Try not to build them too big where feed will be sitting in them for over a week. Keep the DIY demand fish feeder in the shade as your feed will not do too well in the heat nor will the pvc stand up to UV.   It is always best practice, where possible to see your fish during one feed every day so try not to rely on this method of feeding to do all the work for you.   The best time to see your fish is when you feed them as it will give you a clear response.

Spend a few weeks tossing a little feed at the base of the rod to train the fish up to bumping it to get feed. Do your best to weigh a day or two days feed into it if it gets stuck open!

Other than that, enjoy fattening up your dinner.

DIY Demand Fish Feeder

Let’s take a look at the parts in a section to show how they go together:

DIY Demand Fish Feeder

Below is your shopping list and the retail price of them at the time of this build  (18/11/2010). I have neglected to add the short piece of 25mm pipe that goes through  the hopper to support it.   Allow 10 cents…

Really important all metal is 316 stainless steel:
1 3/16 Threaded rod $ 22.00 ea
2 3/16 Wing nuts $ 1.50 ea
1 3/16 Hex nut $ 0.50 ea
1 3/16 x 1-1/4 flat washer Fits the outlet pipe $ 1 .50 ea
1 3/16 x 1′ flat washer On top of the rod $ 1 .00 ea

1 150mm DWV pipe $ 10.00 ea
2 Pressure 40 x 25mm coupling reducer One is the trainer $ 3.50 ea
2 150mm DWV push on cap $ 15.00 ea
1 Plastic bead the size of a marble $ 0 .05 ea
Total bucks out-of-pocket $ 75.05
You can substitute the fittings above for whatever works for you. This is only an example of how to build these units.   It will give you an understanding so you can forth and make it out of anything you have handy, or copy this one. Up to your imagination really.

Let’s get on with it….

Here are most of the components laid out, pretty simply. The 150mm caps can be changed out for smaller diameter pipe like 100mm. By all means if you can get the fittings to work, go smaller if you are dealing with small amounts of fish.

DIY Demand Fish Feeder

I did this part a little backward in my haste. You are better to heat the cap to get a slight conical shape for the bottom cap before cutting the hole to fit the small end of the reducer into.   But either way works.   Cut this hole or shape the cap, up to you.

DIY Demand Fish Feeder

Here we heat the cap to get a sloping bottom so the feed does not sit flat. Simply heat up the cap and sit it on a piece of pipe and push down to get the desired shape.  Be sure to push evenly and dip the cap in water to cool it down quickly.

DIY Demand Fish Feeder

This is sort of the shape you are after for the bottom cap. A little steeper if you can get it.  It is just to force the feed toward the outlet.  In the previous copy of this DIY feeder, I mentioned that you can do without this conical shape at the bottom of the feeder.  Unfortunately, you will need this shape and a steeper one if you can create it.

DIY Demand Fish Feeder

Now we cut the small end of the reducer down to about 5mm left and push it into the hole we cut in the cap.   We do not want the small end sticking up into the cap which will block the feed from getting out.   I welded this one in, but you can glue it if that is what you have handy.

DIY Demand Fish Feeder

This is what it looks like from underneath.   You can use a sikaflex or other adhesive sealant to glue it into the cap. What you have handy and what ever works.

DIY Demand Fish Feeder

Now I used 306 stainless for this, I would have preferred 316 but it does get expensive.  I would avoid using zinc or gal type threaded rods even if they are a little cheaper, they will cause you issue later.   I cut the 920mm long threaded rod in half and threaded on the large washer, hex nut and wing nut about half way along. You can make the rod longer if you like.  Do not over tighten just yet as you will need to adjust it later.

DIY Demand Fish Feeder

This is a little plastic bead about the size of a small marble.   Try for something that is close to the size of the feed you are using but big enough to get on the rod. Aim for a similar color as you feed because you want the fish to mistake this for a pellet floating on the surface.  There are timber ones and all sorts, grab a mixed bag for a few buck from a cheapy store.  I simply heated up the rod with the hot air gun and threaded (melted) the bead on the bottom end of the rod.  This is the same end as the wing nut.

DIY Demand Fish Feeder

Nearly done!  Grab a small piece of pipe like 25mm and cut it the diameter of the hopper (pipe) and leave about 10mm out each end.  We will use this for hanging with later.  I put the cap on the top (which is the lid) and marked it, then measured down from there enough to give the pipe clearance from the cap. Drill the holes through the middle and glue/weld/silicon in place.  Really important to get this as close to the middle of the pipe as possible.

DIY Demand Fish Feeder

Drill a small hole (a little bigger than the rod) right through the pipe in the dead center.  Get this wrong and the pendulum will not sit right.  Then flip it over and drill a larger hole
on the bottom side.  This gives the rod some room to move. Poke the rod through and assemble as the picture.  This top wing nut is what you will adjust the feeder with, so leave a little length to undo to let more feed through later.  Once it is right be sure to spanner tighten the bottom washer nuts.

DIY Demand Fish Feeder

I put a short piece of 40mm pipe in the bottom coupling (below my thumb).  We will be connecting the “training wheels” to this. If you are happy with it, glue the bottom cap on
and it should look something like this.

DIY Demand Fish Feeder

This is a view from underneath where the feed will fall through as the red bead it hit by the fish.  If you make that rod too light (out of plastic) it will move with the water and cause all sorts of problems.

DIY Demand Fish Feeder

Here it is hanging in the tank.   They do not work well hung from rope like in the picture. I did not have time to make up a frame for it but will update this DIY when that is done. Best to mount them stiff and solid, not swinging in the breeze.   When mounting them, the bead should just sit in the water mostly covered by it so it represents a floating pellet of sorts.   Kind of like fishing…

DIY Demand Fish Feeder

One little addition is that second 40 x 25mm reducer coupling.   The “training wheels”.  That is turned upside down and pushed only onto the short piece of 40mm to concentrate the feed right on the bead. Once the fish get the hang of it, remove this to give a wider spread of feed.

DIY Demand Fish Feeder

All you need do is adjust the top wing nut until a few pellets of feed fall out when the rod is gently touched. Over the next few weeks, feed only a bit around the bead in the water. It will take a while for the fish to get used to this new thing hanging over them.  This is where a longer rod can help remove the hopper away from right on top of the water as some fish can be spooked fairly easily.

Auto fish feeder

We hope you enjoy our free DIY Demand Fish Feeder


4 Responses on DIY Demand Fish Feeder"

  1. Jon says:

    I have built one of these in the past and it does work. As you mentioned, it can get stuck in the open position and dump a lot of food. Also, ants found there way to it, but in a pinch it will keep your fish fed.

  2. Thanks for your input Jon.

    Ants manage to find any feed in anything! Like you say, good in a pinch and avoid overloading them.


  3. Frank De Block-Burij says:

    pendulum feeders are known to waste food, because fish often are all too enthousiast, so you should have a way to lock them and only unlock during certain hours
    wasting food not only wastes money, uneaten food also consumes lots of oxygen

  4. iBom says:

    Nice Tutorial Sir its really helping my project now i just need to combine it with my microcontroller