Backyard Aquaponics
A place to discuss aquaponics

Hello, I am very new to aquaponics and have a ton of questions... probably no brainers but hey-ho there you go it takes all sorts... if I intend to use a grow bed that is 2000cm x 130cm what is the minimum number of tilapia I will need to provide sufficient nutrients? If I have fish in the system can I supplement with nutrients? That will do for starters. Thank you.

How deep is your growbed?

Hello, thanks for the interest, the overall depth will be 30cm so we will plant to about 25-28cm I imagine.

Well, for it to be a true aquaponic system, one tilapia. Less than that it would be a hydroponic system. It does not take much to support plants.

hello Ronmaggi, when you say one fish are you just using that to explain the difference between aquaponic and hydroponic? You go on to say that you do not need many fish to support the growbed, I was thinking maybe 28-30 lettuce in my first bed. How many fish do you recommend? Will I need to supplement with added nutrients?

2000cm or 200cm by 130cm?

If its 200cm x 130cm x 30cm then you are around the same size of a BYAP bed. These support a maximum of 25 fish.

You can still get good plant production with much less fish - even 2 or 3 fish with a good quality feed will give you good growth.

If you want/need to supplement you could use seasol/Maxicrop and Chelated Iron.

Update: you may want to take a look at this thread: viewtopic.php?f=3&t=12006

Thank you arbe

Yea, I was only being partially sarcastic, the reality of it is that plants can get by with fewer fish, if your end goal is not to have many fish. Most people's problems arise when hey have too many fish.

Hey there Anthony, welcome to BYAP. You didn't answer the question about the actual size of your GB - is it 20 metres long or just 2m? Also what are you planning for a FT? The fish numbers are minimal for growing veggies etc but the fish density and ability to remove wastes from the FT can be critical.

Once cycled the GB (if 20m long) will handle a very large amount of filtering for your system, so you could, depending on the FT size, have a lot of fish in there. I have an IBC with around 45 fish in it - they are only small so far but I'm feeding them well (probably overfeeding them by some standards here) and my 1 sq m of growbed is handling things just nicely - 0 ammonia and nitrites and minimal nitrates in the water. The GB itself is chockers with plant life - big healthy plants growing almost visibly.

But by the time my fish are (say) 15cm's long I will likely be needing more filtering - I can either add GB's or apply other filtering such as solids filter and bio-filter. I am planning to do both - extra GB's and the filters.

So, have a look around, have a read of The IBC of Aquaponics (main site page) and check out the members' systems for ideas.

Good morning journeyman, sorry the grow bed will be 2 meters x 1 meter 30cm and 30cm deep. what is FT? ahh!! fish tank Our proposed growing area will be around 5sq meters of GB. I get the correlation between numbers of fish and need for filtering, you seem to have a lot of fish, is this just because they are small and you have future plans to alter your system? Or is that the right amount of fish?
we are planning on using tilapia and a tank of around 1000ltrs.
Good pointer to use the members systems page thanks.

One thing I've noticed is, the lack of anybody talking about disease, (health problems with the fish) bug infestations ect. ect. I would have thought that any high density production would have it's fair share? Had any significant problems?

The only time people get health problems with fish is due to under filtration/over stocking of fish.

With your 2m x 1m x 0.3m growbed you can stock a maximum of 25 fish. This is a maximum you dont need to stock to this number - you will still get good growth with 10 or even less.

Bug's sometimes do get to our plants but if you encourage natural predators the nasty ones should be kept in check, besides, bug normally attack weak plants which you dont usually get in AP.

Worst thing I have experienced is caterpillars but Dipel takes care of them.

Good morning... Is it possible to rear Tilapia without having to feed them expensive fish feeds. I have seen that they like worms and rice, corn veggie stuff especially duckweed. Could they live on duckweed alone?

They probably could but they won't grow as fast as if you fed them a good quality fish feed.

A broad diet is important, not only for the fish, but the plants. Duckweed alone won't support much plant growth.

Hello and thank you to arbe and Ronmaggi, someone has just told me that it takes 6 weeks to cycle a system and you can't have fish or plants in there while this is going on. Is this so?

How did you cycle your systems?
arbe got any more recent pics' of your Home system?