Backyard Aquaponics
A place to discuss aquaponics

I am trying to setup my new experimental system to hold barra, if there are any of you that have raised barra please advice me on what can go wrong,
I need to know temperatures, will a cold change kill the fish or will they just stop eating?

Plenty can go wrong with Barra, just make sure you get very large barra to begin with as our season is too short here in Perth to get fingerling to size.

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Thanks for that earthbound, that is what I was looking for, cheers!

I'm doing my own experimentation with over-wintering barra in an unheated outdoors system in Perth, using groundwater to "regulate" the heat; the tank has some insulation around the sides and I have a rudimentary insulated cover over the top.

My water temps have been as low as 13-14C and only one fish has succumbed to the cold (well, I didn't see any other signs which would indicate otherwise). They rarely feed below 18C and are very lethargic. The biggest problem though is disease (I've lost a few); the fish's immune system is suppressed in the cold conditions leaving them prone to getting sick or being unable to fend of parasites and other nasties. Keeping the salt up over 6-10ppt is helping (barra can withstand oceanic salinity 35ppt, but most plants wont!).

In your other thread, you ask about insulation: If I was going to try to this again, I'd obtain a large section of dense polystyrene on which to sit the tank to keep it off the ground, the thicker the better. Wrap the sides of the tank in as much insulation as you can find (I've seen people using R3.5 batts then applying a vanity layer to appease SWMBO). I don't have a proper lid, but a good tight fitting polystyrene lid will prevent heat escaping out the top of the tank; cut the minimum number and size of openings to facilitate services as needed. The lid needs to sited be above the water surface though to allow gas exchange to continue. BUT, all this only keeps heat in, so, where does the heat come from in the first place?

During our sunny winter's days you can remove all the lids and insulation and expose as much of the tank to the sun as possible. One day last week we had a max air temperature of 18C but the water temp got to 23C. In the afternoon, you have to wrap everything back up again to retain the heat collected during the day. This un-wrapping and re-wrapping is a lot more work than it should be (AP is supposed to be easy); if you've got a lot more insulation than a single wrap of 5mm foiled foam, the job gets even bigger. Several (many?) people have tried using vacuum tubes, pool solar heaters and coils of reticulation poly to collect heat without having to unwrap the insulation, but I haven't, yet.

IF I'm still around next year and IF I got SWMBO's approval, I'd like to try a 50-75mm dense polystyrene "plug" lid with about 30m of black poly embedded, with a clear perspex layer. I've got a small low-power aquarium pump which could move a small flow through the piping to collect some heat during sunny days. If there isn't enough heat collected during the day, I can still add ground water (21-22C here) to prevent the temps falling too far; but then you need to keep adding more salt as you keep diluting what salt is there, and you still have to worry about disease, viruses, parasites and sick fish. It's still not an easy prospect, and anyway, I prefer trout to barra!

If you are going to electrically heat the water, be prepared for a massive power bill! Remember, the specific heat of water is about 4.2 kJ/kg.C, so with PERFECT insulation, to heat 1000L by 1C in requires about 4,200kJ, to do this in one hour requires about 1.2kW (or four 300W aquarium heaters at full power running continuously!) In real life, with less than (theoretically) perfect insulation... this problem gets worse! BTW: if you are going to electrically heat your tank, locally 300W heaters are about $50-60 each (CitiFarmers, you can get cheaper online) but you can get 500-1500W kettle/in cup elements from a lot of places for just a few dollars and build your own sealed system (requires a lot of silicone and care otherwise the consequences can be catastrophic, but it can be done) or a diversion system.

Another option: if you cannot move the system indoors over winter, in some circumstances it might be possible to build a temporary structure around the system? But, there's a cost and if you remember some of the kick-ass storms we've had this year... it might all end up in a neighbour's yard?

Thanks for your input bunson,
I got a 300wat electric heater from Woodvale for $30, cost a bit in fuel getting there, but it was worth the trip, I did a test without the insulation over night for 24hours, as you said little difference in water temps but a big jump in power usage, I have thought about the foam for insulation but the thought of chasing little bits around the yard for years is not good,
I am working on a cover for the complete unit now, like a small greenhouse, I found some plastic sheeting 2m/10m clear that should do for the roof, $27 at Bunning’s, still thinking on the frame, possible 20mm electrical tubing as its uv safe, it’s a work in progress,

Cheers

I conducted a small experiment last night...

Yesterday, the max air temp was 21C, with over 9 hours of sunshine the (800L of water) FT temp made it to just over 25C by about 15:30 when I replaced the insulation and dropped on the cover. At around 18:00 the air temp was about 13C and the FT water temp was about 24.5C Normally I "top up" the heat using ground water overnight, but yesterday I installed a 300W heater, it was switched on at 19:00. The minimum temp overnight was about 4C and this morning the water temp is just over 20C (which is pretty close as to what it would be if I top the heat during the night using ground water, but I didn't need to re-salt this morning). 12hours x 300W is less than $2 worth of electricity per night, but that will very quickly add up if it were needed every day and night over winter. Who's to say that next winter wont be substantially colder than this winter?

With better insulation than what I have, especially a tight fitting insulated lid, and a larger mass of water, I reckon it might be possible to retain a suitable amount of heat in the system overnight, so long as sufficient heat is gathered during the day; otherwise supplemental heat ($$$) will be required.

My aim is not to have the barra thriving as they would over a summer growing season, but to have them survive so they may "resume" their growth as soon as summer arrives; avoiding any large and rapid (daily/intraday) changes in temperature.

that’s simular to what I am thinking bunson, I have thought about bringing at least two of the larger fish inside over winter when I get them that is, and raising them so as to be breeders, that would save on fingerling every year and I could sell some excess on gumtree? Or here? As for power kw I made 12kw today with the solar panels on the roof, over 6mw in just over 18months, I sill have a bit of building to do to get my setup how I want it, but still a month of getting the barra, I want them to hit the water running, not in the corner shivering,

My water temp today was about 25.5C and we've a few nice days ahead with cool (but not cold) nights.

re:breeding barra: a couple of notes...

"Hatcheries are now able to spawn barramundi in captivity year-round with controlled lighting and temperature. Juveniles mature first at 3-4 years as males and change at 6-8 years to females; however, under certain aquaculture conditions maturation occurs in about half that time."

"Barramundi are are protoandrous hermaphrodites, meaning that most juveniles are male untill they are 3-5 years old, at this age they will selectively turn female and become sexually mature. Due to the size of the fish at this age it would be very difficult to breed them in a small scale aquaponics setup."

"Barramundi are protandrous hermaphrodites, which means they change sex from male to female. They mature first as functional male fish and then undergo sex change to become female. Studies have shown there is a relationship between size and sex. Most barramundi mature as males at about 50 to 60 centimetres and start to change sex at around 80 centimetres, but only if they are living in marine waters.

In freshwater impoundments, such as Manton Dam in the Northern Territory and Tinaroo Dam in Queensland, barramundi were introduced for the enjoyment of recreational fishers. Here, you can find barramundi weighing over 20 kilograms and over 100 centimetres long, however they are all males. Because of this, restocking is the only way to replenish barramundi populations in these freshwater impoundments.

It is believed that saltwater triggers sexual maturity in males and that they need to spawn at least once before changing into females."

So I need to add salt to my indoor tank?

And a beer or two to my fresh water tank!

We all know the other fish looks bigger after a few beers!

I wonder if it works on fish?

You are thinking of breeding barra? If you haven't had experience n this area forget it.... I hate to be a wet blanket, but it is not simple unless you REALLY know what you are doing.

No I am a novice still, but I was thinking as they lay eggs or spawn depending on size of the fish, wouldn’t it be natural if you had the two different sizes in the same tank at the right time of year? I have also seen a clip of a large fish farm where a guy squeezes the two fish to get the eggs out and you know what, and simply fertilizes the eggs in a bowl, has it been tried on barra before, in searching for clips on barra I came across a fisheries website that do raise barra and release them into the water ways as fingerlings, 30thousand at a time, someone must be doing it, not that I would need that many, but unless you try something you will never know if it can be done, its just a thought for now as I haven’t got my first barra yet, after all someone invented a wheel someone also said when looking at a chicken, I am going to eat the next thing that comes out off its ass, and now we have fresh eggs! good timing I guess,

Ha ha. Nope, there is very minimal if any edible Australian native fish that will breed in tanks, and similar that would even spawn without hormone injection. Even breeding in dams is difficult without tidal summer rains.

Stripping eggs from the hen and medical skills to fertilise is way out of the average persons reach.

Your YouTube adventures are unfortunately leading you astray.

Yes but even Einstein said a hundred people can tell you are wrong, it only takes one to prove that you were right! I am just thinking ahead, I do that, two weeks ago no one thought of adding a paint filter bag with their swirl filter? To breakdown the solids and keep the useful nutrients in the water? This is just my 8th week into IBC Aquaponics, that’s the date my IBCs arrived, everyone seams to be following the last system instead of thinking about the next system? Maybe some of my thoughts on here can make others think outside the square! I am always open to new thoughts, I was just looking at mixing indoor aquariums with outdoor aquaponics, if you didn’t notice I added charcoal bags and sea shells to my bio filter? that’s new on here too! that’s years old in aquarium technology, my water feed to my fish tank is not glued, so I can change it at any time to reduce build-ups in the corners! I can turn off my fish tank or grow beds at will? Using the thread taped valves which can be moved for expansion I have no wasted pipes, I run a AC/DC air pump so I can use a 24hour timer for my pump so I only need to pump water when I want to, all these things and more I have thought off in less than 8weeks? Off receiving my two IBCs. What do you think I will do when I have completed this basic system?

Yes it scares me too!

Sounds like something I would do

What scare people

Only joking Itechnical.

Welcome to the mad house,