Backyard Aquaponics
A place to discuss aquaponics

Hey guys,

i'm from germany and would like to use common carp, yes i know you don't like them.
But i love them, wonderful fish, easy to breed and for starting easy to get.

I know the ratio of 3kg per 100L growbed.
But this means for fullgrown fish.
When i started in april with fingerlings about 15g.
I put 30 of them in my 1000L tank and after saison i think average could be 70-80g.
So i'd 30x80 => 2400g fish for 1000L that should be not much...
When i use the formular i should have 30kg right?

Ok next prob:
After the first year the stay in pond over winter, and next spring its starts again, but then i'm starting with bigger fish, but also small plants.
Was the only idea to eat every fall the biggest one, and uses every year less fish in system?
Or missed i something?


Greetings
Dom

Hi Tiggar

3kg per 100 litres of filtration is the figure bandied about for a mature system. A new system won't support that amount of fish, so it is usually suggested that people start with much less and let the system build its capacity to convert the waste.

If you start with fingerlings that will eventually grow out to make up the 3kg figure then that isn't a bad way to go. As the fish grow the system builds its capacity to suit. It just means no fish to eat for a while until they get to size.

Another option (the one I took) is to get some bigger fish and some fingerlings but of course you have to pick a species that won't eat the little ones , silver perch in my case.

If you have a species where sizes can be mixed then that is the way to go. That way you can keep plucking out the big ones and adding little ones as you go.

What ever kind of fish you like provided they are appropriate to your location/system/situation are fine. If you like carp, more power to ya they can be hardy fish.

The 3 kg per 100 liters of grow bed is "MAX" The way BYAP has been doing recommended fish stocking is probably a bit more sane. They recommend 20-25 fish per 500 liter grow bed (starting with fingerlings and assuming harvesting fish at about 500 grams.)

It is perfectly ok to start with small fish as a new system does need to cycle up to the load. If you were to toss the "MAX" into a new system, the ammonia spike would likely kill the fish before you got it cycled up.

With you cooler climate and probable multi season grow out. The fact that the fish will be bigger the second spring is probably ok since the spring start up of feeding will likely be slow as the temperatures will rise slowly so the system should get a chance to cycle back up even with the larger fish. During that spring re-cycling you will of course need to watch ammonia and nitrite levels again since spikes could happen. I expect you will also need to watch for algae blooms seasonally as well so keeping the water shaded will probably be important.

During winter you will need to make sure the fish tank surface doesn't freeze completely since the most common cause of fish deaths in frozen ponds is bad gasses building up, keeping the pond aerated over winter or keeping a hole melted in the ice may be all that is needed

There are several members who have re-started outdoor grow beds in temperate climates each season. There are other members who have kept systems going in heated greenhouses in cold places though the winter is usually really slow for the fish but some plants like cold thought they would appreciate more light if they could get it. However, watch for freezing pipes or the water freezing where it enters the grow beds.

Hey FF,
thanks for your response.
My system runs since april this year, so it isn't new at next spring.

But i'm right that the 3kg per 100l refers to the fish weight at end of season.
The max weight which fish will have in this run.
Yes of course this belongs to a good growing planting system.
Do you filter the solids with a prefiltering swam or something else?
Actually i decided to let to solids flows in the growbed for worms.

Ok what i learn was to mix the fish, also i can start with some fingerlings, and the following twice years i always add the amount which i want harvest.

Example:
Starting with 12 fingerling 2011 with 8-10cm (15g)
End of 2011 12 fish with 18-20cm (80-100g)
---------------------------------------------
Adding 12 fingerlings 2012 with 8-10cm
End of 2012 12 fish with 18-20cm ( 80-100g)
End of 2012 12 fish with 34-36cm (600-800g)
---------------------------------------------
Adding 12 fingerlings 2013 with 8-10cm
End of 2013 12 fish with 18-20cm ( 80-100g)
End of 2013 12 fish with 34-36cm (600-800g)
End of 2013 12 fish with 40-42cm (1400-1600g)

The 12 biggest will be eaten and only 2013 will always replays every year :-)

That sould be fine, when i calc 12x0,1kg + 12x0,75kg + 12x1,5kg => 28,2kg.
So i can add some fish for safty :-)

Should probably be ok but beware that you are going to be doing a bit of a re-cycle each spring so be prepared for possible HSM's each spring through fall since once you get to 2013 you will be running near MAX and many people find they have issues with spiking and such when running at MAX. Be prepared to monitor closely and deal with issues if they happen.

What would you do ?
What do you mean with HSM's ?
How much do you drive at your big system?

Yes the maximum at the end of season would be 3kg per 100 litres.

My system runs all year and I use rolling tally like you describe, where I have many different sized fish that would give a total of around 3kg per 100 litres. If you are running only for a season then shutting down then you would have to be careful each time you start up because the system would have to rebuild its capacity to handle the waste.

I have run more than 3kg per 100 litres for a time where I had many bigger fish that I kept on a maintenance ration rather than a growth ration. Lower feed input in relation to fish size enabled me to do this.

No filtering for me, I just let the worms eat the solids

My situation is a bit different with year round growing. (My bacteria doesn't die back in the winter.) I am also running the 2:1 ratio with twice as much gravel as I have fish tank.

Even so, when I'm feeding heavily and I have the full MAX load of fish in there, the system can become a bit unstable and I've gotten the occasional nitrite spike.

HSM could stand for high school musical (almost tragedy with lots of drama?) or Holy Sh!T Moment. Generally this means anything that might go wrong and may kill fish or damage a system. Most of them are due to water leaks or power fails that leave fish high and dry or without filtration causing death. But it can just as easily mean spiking levels, pH issues, Bacteria failure or anything bad.

What to do during a HSM due to re-cycling or spiking due to overstocking (or even just stocking near the max) well generally stop feeding. In extreme cases water changes might be needed. Make sure there is plenty of aeration and water circulation through the filters. Add filtration and even start removing solids if the situation proves that you are stocked beyond the system's ability to cope. Or the other option is to harvest more fish and reduce the overall stocking to a level where the existing system can cope.

What the exact levels should be will vary some what depending on the system, situation, climate and fish type.

Thanks for your helpful postings.

Because the ratio, so i've a different meaning about this.
When you have twice the amount of growbed its impossible to flood it.
Ok now anyone says, no problem i use a sump.
For me the water of sump and fishtank is one total capacity of water!
So i think you're back to 1:1 :-)

As i chat with a german biology we both decided that 1:2 was the better choice.
The fish has much space, the water chemistry is stable and you only have to take a look at the liter of growbed for stocking mass, right?

I'm happy that i know where i can find some please which are crazy like me )
Feel sorry with me and my bad english, i hope its ok for conversation here.


Dom

Your English is good enough to follow Tigger...

As to your biology friend... and the suggestion that ...



Well yes and no... certainly stocking to your growbed/filtration capacity is the correct determination.... and extra water will give stability... and increased oxygen carrying capacity...

But you still need to filter/turnover the volume of water.... and if you don't do that frequently enough.... and/or you dont have sufficient growbed/filtration capacity to match your water volume...

You could build up dangerous levels of toxicity... before you noticed.... and things could go downhill fast... especially when you approach maximum feed rates... and fish growth...

IMO... a 1:1 ratio... with bio-mass/stocking matched to filtration capacity.... is a minimum... 2:1 preferable...

And there are other options available that negate the drawdown on the fish tank.... that don't necessitate a sump...

Yes Rupe is right.
You can get away with the slightly larger fish tank to an extent but I've seen situations struggle to maintain water quality even when the fish load was well below the grow bed capacity when the water volume is huge. A grow bed can really only handle so much water in an hour/day and if the fish tank volume is too big it can be really hard to find the right balance.

A 1:1 system is a reasonable half way point so long as the system only gets stocked to the grow bed capacity. (The biggest danger is that people tend to try and stock to the fish tank rather than the filtration and wind up with problems.)

And as Rupe said, there are ways to increase filtration without needing to go to a sump. The Aquaponics Valve (sequencing or indexing valve) is a great case in point which Rupe could help you with if you later decide you need to add grow beds.

My Big system has a 2:1 ratio of grow beds to fish tank but my sump tank is less than half the size of the fish tank and this works in my system since I am running indexing valves. So even if you added my sump tank volume to my fish tank for the ratio calculation, I'm probably still 2:1.4

Hello my friends,
i've some questions.
This year i'm using my pond (10.000L) with two gravelbeds which contains 12t gravel.
I stocked in april something about 250 small carp and 2 big 3kg fish.
All starts to grow and flower, and today i'm feeding 300g each day.
I think its a lot, but unable to read any kind of nitrate.
But wanna have a reservoir of at least 10mg/L.

Whats your experience about the amount of fingerling?
Not the number of fish, i think about the weight at beginnig for x liter growbed/fishtank.


Kind regards
Dom

The area of beds are 27m²

I will say that carp are extremely tough, I first started with some from a nearby dam, they were flapping around in a foot of water heading for a not so distant death. When I got them home and put them in my FT they were bleeding from the gills, mouth and every other opening. Out of 30 only lost 5 in the end. Amazing species.

Thanks for your reply.
I don't know if we're talking about the same carp?
I mean the common carp...
http://www.naturfoto-cz.de/bilder/ander ... -20524.jpg

How much would you stock per 100L at beginning of season?


Dom