Backyard Aquaponics
A place to discuss aquaponics

There is heaps of material... search for:
stocking density
fishtank to growbed ratio etc.

Or look at the following forum: Useful Information There are a stack of good threads there on ratios

eg look at this thread I found
The Ratio question and sump tank tips.

Also, don't change the size of your text unless necessary, it makes it hard to read and appears that you are yelling.

The balance between plants and fish is not as important as the balance between bio-filter and fish. Without the proper amount of filtration, the fish can't survive well at all without constant water changes. If there is enough filtration, the fish will do well and you can add more or less plants as needed.

The filtration is the most important part of aquaponics and often the most forgotten.

An aquaponics system can be run or cycled fishlessly and run ok.
A system could be periodically without plants and only need some water changes to keep nitrates under controll.

But and aquaponics system without enough filtration won't be much good for the fish or the plants.

It is all a balance If there are not enough nutrients for the plants, then you either need less plants or more fish. If there are too much nutrients, then you need more plants or less fish. These levels will fluctuate and many system grow fine plants and never see nitrate readings, so long as the plants are growing well and not showing signs of nitrogen deficiency, then all is well.

Welcome, Mohammed.

I agree with what is said above. Basically

1) Fish are healthier with more filtration, oxygenation, and temperature stability. So the more water and growbed you have, the healthier they will be.

2) The amount of nutrients plants need varies with temperature, plant size, plant type, etc. So you can either try it and find out for each plant type or see what other researchers have discovered or just try it and see. Most of us simply plant what we want to try and see how the plants do. There is a lot more on this in the forum.

3) The amount of waste (nutrients) that fish produce will vary with species, water temperature, age, and feed. Just as a rough measure, I read somewhere that 100 grams of food per day fed to tilapia can support one square meter of lettuce. Please do not take that as being true for your system, it is only a rough guide!

4) Lots of filtration is costly and uses up lots of space, so we tend to try to crowd fish and plants. This saves money but tends to increase problems with fish health and insects on plants.

Have fun!

Thank you for these links
I will read it.


I'm sorry
I did not mean it



Thank you very much
This is what I was looking for exactly




Do I have to use this type of filters?

I thought that the plants who do the filtration!!
I think I have to learn a lot about this system before you start.
thanx bro

Hi and Welcome...
Yes that pump will do but take the filter spounge out

That is a very small pump, I wouldn't think it would suit a system bigger than 500 litres.

Better I look at the photo and read the text

Welcome! It will become easier to suggest stuff to you if one has an idea of the size of the system are you planning and pictures of where you are going to put it.

The plant DO NOT do the filtration... The bio-filter or growing media where the bacteria grows and also where the solids are captured DO the filtration.

The plant use the nutrients produced from the filtration to grow...

I guess what the members are all advising is that the question is NOT the Balance between Plants and Fish, but the Balance between your Bio-Filtration and Fish...

As a general guideline, it is about 3kg of fish per 100L of water and you will need at least 100L of bio-filtration... What is commonly referred to as fish tank volume to growbed (filtration) volume...

From the nitrogen cycle, nitrate is produced and used by plants to grow... And provided you have planned your growbeds well, you will just need to plant more plants or less plants to use the nitrate accordingly... It is actually quite alright to have some nitrate reading in the cycled system. In other words, an imbalance where the fish is producing more waste than the plants can use...

In case that is not clear: don't buy a filter because the gravel (which you may or may not be using to grow plants) is your filter.

So a quick summary is.

You don't need a filter on your pump, the media (gravel or expanded clay etc) host bacteria that filters your water.

The ratio I have seen on a site some where suggests, 10 Litre of growbed to 10 Litre of Fish Tank to 1 Fish.
If you have less growbed volume than you do fish tank volume, the ratio should be based on the growbed size.

An example is:
1200 Litre Fish Tank
500 Litre Growbed
50 Plate sized fish (max).

Which site was listing this Shivaz.... IMO... it is totally misleading.... and at 1 fish/10L.... gravely overstocked... even with a growbed volume of twice the ratio...

A safe stocking density for plate sized fish would be about 30kg/1000L.... or in he example given of a 1200L tank.... about 36-40 fish.....

With a minimum of... IMO.... 1000L of growbed....

Want to push your density higher... then you need to double the amount of growbed volume again IMO....

Giving a ratio of 60kg/1000L.... and 2000L of growbed volume...

1 (plate sized/500gm) fish/10L.... equates to 50kg/1000L

Who is recommending the values quoted???

And what sort of aeration do they quote??

And how many fish kils have they had???

Hello Rupert

Wow, glad I bumbled in here! Could have been having some issues once I got to actually putting fish in!
Thanks for the heads up.
I am sure I have found that info on a few sites, but here is the one I think I found it off:
http://www.diyaquaponics.info/fish.html

To be fair, the next paragraph after talks about how important aeration etc is.

How Many Fish?
How many fish you can grow is referred to as your stocking rate. Determining your stocking rate is difficult because there are so many factors that influence how many fish your system can hold. If your fish are fingerlings you can have many more of them in your system than you could if they were grown out and ready for the table. The size of your growbed is important too as this determines the level of biofiltration available to your system. A recommended ratio for your system is 1:1, that is for every 10 litres (approx 2.5 us gallons) of fish tank capacity you should have 10 litres of growbed capacity. I would suggest no less than 10 litres of fish tank capacity per fish. So in this example if we have 1000 litres of fish tank capacity and 1000 litres of growbed capacity our maximum stocking rate is 100 fish. Clear as mud?

Now if you had a fish tank capacity of 1000 litres but your growbed capacity was 500 litres I personally would not suggest any more than 50 fish for this system as the biofiltration is not likely to be adequate as the fish get bigger. With 20 litres of fish tank capacity per fish you will probably have happier fish too.

Aquaponics is a balancing act at all times and testing your water regularly will alert you to any problems as they develop. Avoid the temptation to overstock your tank, particularly if its your first effort. For starting out perhaps consider equal growbed to tank capacity and a stocking rate of 20 litres per fish. When the fish are small only plant out perhaps half your growbed to make sure your plants dont suffer from a lack of nutrients.