Backyard Aquaponics
A place to discuss aquaponics

Hey,

Got a question... I made calculations and I need 12kg of fish in one cubic meter of water but. How can I always have 12kg of fish in one cubic meter of water with fingerlings which are going to grow up? Is there a method?

Thank you

Mathias

As with all things aquaponic it "Depends"

Just keep your nitrate levels in the 10 to 40ppm range

This is controlled by the amount of feed you put in

Water changes if required

And how many plants you have their size and of course fish numbers

You may or may not have seasons where your fish stop feeding (my fish shut down during the cold season) this will effect your levels as well.

Its really a best guess situation and how you manage your fish and plant rotation

Small plants use less nitrate than big plants

For example , If you replace your big fish with little ones this is a good time to replant

Yep, always "depends" as Terra says.... start with 20-25 fingerling, plants will grow faster when there's more nutrient available and slower when there's less so you dont have to stress too much.

in sy2 I've got 60 3-4" trout fingerlings in one 1000 lt IBC being filtered by 1 1\3 year old 6m2 of scoria F&D grow beds with dozens of seedlings between 2 & 6" tall. The weather is consistantly cool here for the last few weeks so the fish consume a little less food than they would with higher water temps.
Sy1 has 6 large trout who are not eating as much either and are being filtered by the same amount of space, volume and planting density.
Everyone seems happy. Once we've consume the larger fish I'll transfer 30 of the smaller ones to sy1.

Too many things are dependant on the answer. Generally I believe, "small plants with low consuming fish" and "mature plants with higher consuming fish". This can be tweeked by varying the amount of fish feed and having a seasoned GB helps even out the spikes.

i have two tanks. Big fish (from last year) in one, fingerlings in the other. Harvest some big fish as fingerlings grow. Then, each spring, put the grown fingerlings in the 'big fish' tank and get new batch of fingerlings.

one of my two tanks is my sump tank, which means I can't let my sump tank water level drop too much.

also, my 'big fish' tank is never empty so at this point, some of my big fish are a few years old.