Backyard Aquaponics
A place to discuss aquaponics

https://www.youtube.com/watch?v=E7b_yW-MPbg

I have sunk the grow bed pipes into the sump tank, all is working fine, I have cut back the algae in the fish tank, not that there was that much to start with, the fish are getting fat, FT temp was 20deg today, so I am of to get my first barra Monday, I still haven’t decided whether to get 10 or 20 barra? The fish tank has 700ltrs the sump tank is a 500ltrs atm, but the system is running, the grow beds are filling up!
Any thoughts on fish quantity or advice on my system is appreciated,

How many fish you get depends on how much filtration you have. What is the volume of wet media in your GB's and the capacity of your other filtration?

500ltrs of clay media, plus a swirl filter and a paint bag filter to collect any floating solids, I also have a AC/DC air pump in the FT/ST plus 3 venturis to add air to the water, one in FT two in ST, plus an overflow that also adds air to the ST, I at the moment have the ten goldfish to be removed indoors shortly, once the barra arrive! I have a 700ltr FT and a 700ltr sump tank, running at 500ltr ATM, filter will do 600ltr plus per hour,

My amateur opinion is that you could happily go with either 10 or 20 fish if you grow them to an average 500g each.
I'm assuming 25L of media per fish. Which seems to be a generally agreed upon safe ratio for most backyard systems.
20 fish would be packed into 700L about as tight as I'd be willing to stock barra. Bear in mind I've never grown them and it's more to do with my assumptions on animal welfare than anything concrete.
You should be safe to run 20 fish if you want.
(My opinion is only theoretical, I'm just feeling chatty and it's only me and the PC here tonight. Must distract myself from buying stuff online... )

I'd be more interested in what the minimum water temperature was last week, as we've got similar weather coming up this week; if the fish are coming from heated indoor tanks, there's a good chance that with a few chilly nights to come the fish in an outdoor system wont adapt fast enough to the cold, and die. Even fish used to 28C may quickly die if dropped into 20C. I've kept my barra all winter and even now they aren't really happy until the water temp is over 25C... I'd hate to think how fish who have spent their whole lives so far in warm water are going to react.

It's been said many times before; to minimise stress on the fish, match your water parameters to the source.

With barra: no more than 1 fish per 25L of wet GB (filter) media, but in a new system, it's safer to reduce this number by at least 20% in the first year, always round down.

Thanks guys for your input, the fish are around the corner now, they are in the same weather conditions as I have, I will have a look at them on Monday morning, if they don’t look the grade I will take a trip up to Woodlyfields ? According to the guy that sells them down the road, they only grow at 22deg, but they are happy below that temp?