Backyard Aquaponics
A place to discuss aquaponics

I know this has been said over and over and over on this forum but you still come accross people saying that you can stock 1 fish per 10L or 100 fish in a 1000L IBC.

The first person I know of to promote this stocking density has apparently stated many times that he first said this with qualifications and caution but it appears that at least some of the people that he supplies with advice and material still advocate this stocking level without any qualification.

Some would think that this has been done to death but look at this screen shot from the Ballarat Hatchery Website. Where many members on this forum and others get their trout.





One of the members of the Ballarat Fish Acclimatisation Society that run the Ballarat Hatchery I have been told is a distributor of the individual mention above and it would seem that he would be the one responsible for the inclusion of this dangerous stocking density on the Ballarat Hatchery's website.

I'll be going in on Saturday to buy some fish and I'll be having a word to them about this.

It might be an idea to sticky this.

Go get 'em Stuart

I put 200 trout in a cut down IBC that held 800L once..... mind you they were only in there for one day

I put 100 fish in a 20L bag once.

They were fine for 1hr with pure oxygen.

I wonder what the author meant by 'semi commercial levels'?

Could it mean that the enterprise doesn't make/lose as much money as a fully commercial business?

Does it mean that the operator draws only a part time income from the enterprise and, since they have other sources of income, efficiency/profit is less important?

Perhaps what is meant is that the annual output is only small.

I reckon that, any way you look at it, the term 'semi commercial' is meaningless without clarification.

Even semi-commercial would'n't cut it.

Assuming a harvest weight of 500g then prior to harvest density would be 50kg/m3 which would be 10kg over the theoretical maximum possible without pure oxygen injection.

Even if the harvest weight was dropped to 400g then the density would 40kg/m3 and such a level would be seriously on the redline. If anything went even a little wrong, just a tiny bit wrong, then you could have dead fish in minutes.

You would have to have a serious backup system beyond just air but circulation as well. In addition to just backing up against power failure you would have to also include DO monitoring and control among other things.

My greenhouse system has 900L of growbeds (6 black tubs) and a 500L fish tank. I have tomatoes, peppers beans and lots of strawberries all growing well.
There are 4 murray cod in the fish tank

I guess they want to sell fish don't they? And if they die, you must have done something wrong, try again buy some more.

There's a local supplier around perth who is recommending way too many fish. We tell people the right amount to put in, then they contact him and he suggests they go higher stocking levels...

If they saw the size of my cods, it would bloody near change their minds

Good luck on Saturday Stuart. I'd like to think you point out their error and they change their ways. But I imaging you won't be the first to tell them something helpful and be ignored. Greed, self righteousness, bloody-mindedness, whatever. They obviously don't have their customers best interests at heart.

The guys that i have dealt with down there are fantastic, never had any issues.

Lets hope they take your advice Stuart but i'm pretty sure they are not the ones who maintain the website

I dont imagine you would get your trout to anywhere near that size in a bulky. You can see the size differences in different systems with different stocking densities on here.

I agree with you 100%, just saying that without grading etc, you are not going to get close to that harvest weight anyway.

Hopefully they do change their website. It isnt so much for people on here, but the people who have a go without much research who will suffer the most.

not to defend them, but that's doable with good aeration, good water flow, lots of filtration, (600+ gallons of grow bed) , battery backup and generator in case of power blips.

IIRCgrowing power said they had a fish per gallon of water in one of their systems at one time. The water quality was horrendous but it seemed to work for them.

The more concerning part is that they speak in terms of fish tank volume and not filtration.

so the norm is 1 fish per 20-25ltres of filtration media?