Backyard Aquaponics
A place to discuss aquaponics

I gladly stand corrected [s]'mam[/s] [s]sir [/s]... 'mam

Hi all,
I am Rick from Wynyard (N.W. coast). My interests are permaculture and woodwork. I am keen to get an aquaponics system going. Seems we have only one choice, trout. Thats O.K. but how quick or slow do they grow. I think I read somewhere on this forum that they take 18 months to harvest? Is this right, seems like a long time. The system I am contemplating is small, a 350 litre tank and about 18 metres of square section downpipe gully for a NFT system.
I anticipate a 12v air pump to ensure air when blackout occur.
How much water flow is needed for the trout? The NFT system only requires a trickle.
How many fish should I stock?

Any ideas or help very welcome.
Thanks for the interesting site.

Regards
Rick

Hi Rick, welcome
I can't grow trout here, but I don't think 18 months is right. Some one will be on soon who can help you with these questions.

hi rick,

dont be dissapointed with trout, they ROCK! i'm eagerly awaiting winter so i can stock my rainbow trout again. they grow QUICK.

i took mine from large fingerling (sorry cant remember the weight or length) to approx 700grm in around 4 months!

check out the last few pages of my thread for some pics.

A word of caution though, try and get your system set up and CYCLED during the warmer months as i found it much harder to get established with dads system in the middle of winter.

Steve

Trout can be done in 6 month from egg to 400g in water at 15°C. You might be able to do them in around 8-10 month and have a proper quality flesh, don't forget to purge well to get all the fat out of the flesh.
Trout don't need much water flow as long as the dissolved oxygen is high.
Aerate a lot and run a trickle trough the NFT.
Go big with plants because trout food is very rich in nitrogen and phosphates, and trout could get sensitive if the water isn't clean enough.
Have fun and maybe you could try yellow perch on a two year cycle.
Good luck

Thanks Jaymie, Steve and Amacafish,
It’s good to hear they can grow quicker than I thought. This web-site (backyardaquaponics) tells me that for ultimate stocking levels of around 6kg of fish per 100 litres of water require a ratio of grow bed volume to fish tank volume of 2:1. I assume this refers to a flood and drain system but I am familiar with NFT so that’s what I will do, a NFT system. It seems to large to have a 700 litre grow area in NFT to compliment the 350 litre tank but as Amacafish states, I should go big with plants. I can't see much problem that could occur with having too large a garden area but more problems could occur with to little foliage or plant nutrient uptake.

Thank you for your input people.
6kg of fish per 100 litres. Could I then stock say 20 trout in my 350 L (stock water trough) tank?

Thanks
Rick

Rick, those ratios are for highly experienced users only. You are better off starting with about 2Kg of fish per 100L and whatever growbeds or channels you can get started.

All depends on the size of the fish, rick!
Make your system modular to keep the nutes high enough for the plants but low enough for the fish. Taps on the NFT trays opened alll along the growth of the fish would be perfect. Don't forget do do a biofilter before your NFT trays also. Say one flood and drain growbed linked to a small sump that runs into the NFT trays and back to the fish could do it...
Let your creativity work and keep us up to date.

Yep you'll definitely need a bio-filter/growbed before your nft channels to remove the solids....

Don't get too wrapped up in the ratios Rick.... as Jaymie says... they're an optimum and minimum requirement to balance a mature system and an experienced owner at stocking levels of 6kg/100ltr

Also they were calculated with the use of gravel (or other media) growbeds in mind to provide not only capacity for the bacteria to colinise and convert ammonia to nitrates for plant uptake.... but ALSO to provide a means of capturing, filtering and converting the suspended solids before returning the water to the fish tank.

With NFT, you'll have to remove the solids before hand anyway.... so you might as well utilise normal growbeds with the NFT as an ADDITION...

To rely on NFT alone would IMHO require a considerably large volume/area of NFT channels to balance anywhere near stocking densities above 3kg/100ltr....

A normal 6 channel x 6mtr hydro table uses about 60ltr max recirculating nutrient solution.... obviously not all of that, probably about 1/2... plus reservoir.....

In AP... if we assume a higher flow level in the channels (not necessarily the case).... we'd still be hard pushed to exceed 50ltr....

So to turn over a 350ltr tank once per hour you'd need to deliver that volume through your NFT channels 7 times/hour

Typically you'd have about 20 - 25 net pots holes.... thus plants per 6mtr length of channel... so for 18mtrs of downpipe/channel... you're only going to have about 60-75 plants to actually absorb the nitrates and thus clean your water.....

Just not sure that the amount of plants will be sufficient to "polish" the water of 20 trout on it's own..... I'd be putting in about 4 half barrels of growbed as well I reckon....

Make sense... anyone??

Mmm, I recon you'd be pushing it to get a trout to 400gms in 6 months from egg. Most guys here buy their trout fingerlings in May (once its cooled down) when they are already 9 to 10 months old, from there you can grow them on to edible size over the next couple of months.
Problem you are going to have Rick is that I am pretty sure you wont be able to buy any Rainbow Trout (which are the fastest growing) in Tassie unless the fish hatchery delivers them to your door which may work out to be too expensive for just a couple of fish. On the other hand most of those streams up near you are full of small Brown Trout, I'd just shoot out one weekend and go catch a few to get yourself started. I agree with Steve and I'd be doing soon whilst you have some warmish temps, for Tassie anyway.

I'm talking of commercial trout farms I've seen during my studies.
6 months is for the top batch, 8 months for the slow batch. And sorry I forgot that they are triploid rainbow trouts with liquid oxygen and continuous computerised fish feeding, and lights on at night.
Pushing a fair bit as you say but possible.
The problem I see with wild trout is getting them onto pellets, can be done but is quite difficult. Best id to mix pellets with fresh food for a while to get them used to eating pellets at food time.

the trout i got last year were as trout man described. they were already trained onto pellets from the farm. at around $1.50 - $2.00 each they were the best money on fish i had ever spent.

I grew rainbow trout last year for the first time and would highly recommend them them as they are such a fun fish. Theyare not shy (like Barramundi) to feed and clear the water like dolphins which really put on a great show for the visitors, they arequick growing and taste beautiful.

This Tassie thread seems to have gone a bit cold.
Having just completed a 3 week holiday in the apple isle, it is about time we got things going in this delightful state.
PS...
I just got back to Adelaide and despite the heat wave, my system is going gangbusters with heaps of toms, spinach, lemon grass. rocket, peppers, chillies, lettuce, spring onions and parsley. and that is with 25 goldies...100 SP's are about to go in.
I have friends who run a fabulous B&B on the east coast and who are itching to put in an AP system.
I have agreed to go back and help them install a system but we need some more input from our colder states.
It looks like brown or rainbow trout is the go but we need some more details.
Monya and I will be discussing the details of tanks, GB's, pumps etc. but we want details/experience from Taswegians which would be really appreciated.

peterall

I dont live in Tassie (yet) though I have a property there and spend time there (usually chasing trout) every year. The hard part of setting up a system in Tas is going to be sourcing some fish as they would have the strictest rules in the country without a doubt. There are plenty of Trout farms about but legally you canot just waltz in and buy them as you can on the mainland. This has come about as in the past people would buy some fingerlings and then release them in an isolated lake so they could have there own secret fishing spot.
There is a Salmon farm near Deloraine and last time I was there he was setting up a Aquaponics system using his Atlantic Salmon.