run a system at ~constant biomass?

[Greener]

The system I'm considering building will have four fish tanks, one tank stocked/harvested every two months with Tilapia fingerlings (expect for the first 6 months where I will only be stocking), as I am expecting roughly an 8 month growout for each tank. I chose this design because I read somewhere (in one of the UVI DWC system papers I think) that it's best to run a system at a ~constant biomass. What do you all think of this?

It seems like a lot of people raise one batch of fish at a time, then restock. I would expect that this method would lead to big swings in the nutrient levels of your system, adversely affecting production. How do the plants react if their power source (big healthy fish) is suddenly replaced by little fingerlings?

[RupertofOZ]

Most people don't have multiple tanks Greener...

[Greener]

How do the plants react when the single tank is harvested/restocked? Does this induce more flowering, maybe?

does anyone here run a continuous harvest (FT-rotating) system?

[Murray]

Hi Greener,
You have raised a good point re constant bio-mass. It is often the practice in home systems to harvest all the fish out in one shot which can cause swings in nutrient as you describe. This is because most home producers only have one tank systems.
If you were running a commercial system you would be more concerned with maintaining a constant nutrient level, but most home growers are not too worried about that.
Naturally enough, if you wish to be "full on" and very serious about home food production then you are on the right track.

How much effort you are prepared to put in coupled with the level of infrastructure you are prepared to invest in will determine just how much food you can successfully produce.

[Greener]

Thanks Murray!

Indeed, my goal with this will be to maximize production, so I think I will go with the multiple FT setup.

BTW -- I just picked up your 2-DVD set from my mailbox (ordered from Silvia at The Aquaponic Source). About to watch the first disk. :)

[dufflight]

Was only thinking of constant biomass in relation to my next system. Once fish get to a nice size there feed can be cut down so they don't grow much bigger but are kept closer to a usable size. Then it becomes more about how many fish to keep the system going when most of the ammonia is coming from there gills. On a lower feed rate more fish could be kept in one tank to keep the system runnng while the next batch are growing.

[fishfood]

Thats ok but if they are trout or barra there wont be a next batch

[dufflight]

They do tend to eat each other. My COD keeps following me when I go past his tank.

Was thinking more silvers or catfish. Would be harder with the larger mouth fish unless temp was used. Eg colder weather keeping them off there food.

[reet123]

Ya..dufflight you are right. Its good option for them.