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!

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

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).