Els Engel:
I have a memory like a sieve. Luckily I made some notes and I found out it's 500 grams of fish per 20-40 liters of water. That's for adults, according to Bernstein.
I have found the same quote and made a little calculation for a 1000liter tank:
1000 x 0,5kg fish / 30 liter = 16,33 kg fish per 1000L
This is maybe to much room for the fish. But our tanks are smaller
I found in Nelson that ideally you should stock the tank with <20% of the total bio-mass (fish weight) that our system can support.
+It reduces fish mortality
+It leaves room for them to grow
So what can our system support?
Some sources say that its possible to have 20-25 fish on 500L of growbed.
The tower has 3 layers of 10 x 10 x 3,5 dm = 350dm^3 = 350L per bed
One tower has about 1000L of growbed this can hold 50 to 60 fish (500gr) mature fish per tower