Perhaps I am winning.

I will begin this post with another gratuitous picture.
The deer in this shot have been transient in this area for several years. We have seen one or two on an infrequent basis. However in the last month or so they seem to have taken up residence. And in somewhat larger numbers. I first saw, and photographed, this group of four on 27th of October of this year at 7.30 in the morning. And now they have started to appear all over the place. We now seem to have a group of five or six who can often be seen down near our bore. And the resident mob don't include the two bucks seen in this picture. And I had to dodge another one when on the way into town a couple of weeks ago- in the mid morning. That animal was about 8 or 9 clicks from here on the road near Little Burra Road. So far I haven't noticed any roadkill deer but it is probably only a matter of time.
I suppose we should be attempting to control deer as they are feral but I can't bring myself to do so. Bit too cute and cuddly. Also it would be a waste not to eat them if shot and I don't really fancy the whole business.

And so back to the aquaponics.
In the last month or so things seem to have finally begun to show the sort of growth in both plants and fish that I have always thought were possible.
My little heater for the fish water is getting the temperatures up into the low to mid 20s and this is clearly better for the fish. They are eating lots of pellets and on one or two occasions were so hungry that they even came to the surface for food. This is unusual with my Silver Perch which would have to be the most "chicken" fish I could have picked. Some guests don't believe that I have fish as they have not seen them- even when standing right next to the tank!
I have again tried and failed to get adequate pictures- the fish are too nervous and the light levels are too low. Even my new "you beaut" digital SLR camera can't catch them. However just to prove that they are there I have included a fairly poor shot taken a week or so ago. The biggest are probably now close to 140mm in length- basically about a hands length long and perhaps half a hand wide. They are quite deep in the body. When viewed from above they look to be perhaps 25mm or so "fat". The smallest are still only 60mm or so long- looks like we will have a good long period of harvest. The white stuff to the left of the picture is out of focus azolla.

The vegies in the grow beds are growing well- we have had lots of peas and lettuce so far this month. The asian greens are again doing well as is the spinach. I have also planted some chillies for colour. Went shopping to a garden centre the other day and I couldn't resist them.

I am convinced that my last major problem with the whole setup is not enough light. The plants grow but they struggle with , at best, only 4 or 5 hours a day of full sun. I don't want to put more polycarbonate onto the roof- it is a shed after all and sun in not good for all the other things stored in there. Solution may be to simply grow plants which tolerate lower light.
The last picture shows various lettuces and some beans and peas which are doing well. This is the third lot of peas Di has planted. Actually it is the fourth but the third turned out to be sweet peas which were incorrectly labelled.

The outside azolla production is going very well. I am no longer harvesting and drying for the fish as I have a 10 litre bucket of dried leaf in stock. However the new chooks go bananas over fresh azolla. So they get a small bucketfull most days. All from the 1200 litre stock trough. The growth in the blue barrels is disappointing and I will have to work out how to improve that. I suspect that the water gets too hot as it is shallow and in full sun- perhaps a little shade cloth cover might be the go.

We had about 7mm of rain last night but it is still very much drought here and again I am reminded of the need to be conservative with our water. And so aquaponics must be one of the answers.

Warmer weather

Finally some good news on the fish front!
The water temps are now in the 16-17 minimum to 19-21 maximum ranges and as a result the fish are feeding voraciously.
I was worried that a diet of live food over winter might have spoiled the little fishie palates to the point that they would not eat the pellets which are the main food source.
However the first offering of pellets was eagerly accepted- as was the first seasons chopped earthworms and my home made formula (liver, eggs, prawns and azzolla).

I reckon I only have about 40 or 50 Silver Perch left after the winter. And I can't see any of the catfish so I suspect they all died. $300 down the drain so to speak.
I don't yet have a good picture of the fish as they are very reclusive most of the time. However I have indulged myself with a new camera which promises(?) more manual focus and so if I get the time of day right and there is light in the right part of the tank , I should be able to get some shots. The biggest of the fish are now perhaps 100 to 110mm long and looking good!! Given that they are Survivors it is almost unfair to consider eating them - but I think we will manage to do so- perhaps even before next winter.
Actually on a slightly gross note- the dogs discovered that I had thrown the dead fish out onto the ground in front of the shed as I scooped them out of the water. And so they ate all they could find.
Even after I realized this was happening and started burying the bodies the dogs dug them up if I was not watching. I guess it is all just good use of the protein.

The warmer weather has also restarted the growth of plants. The peas Di planted in June of this year have finally taken off and we are now picking lovely fresh sugar snaps. Some of these even make it to the kitchen for cooking.
The top 2 pictures show the attempts made by the peas to escape the shed. Some are perhaps 6 or 7 feet high.

The coriander visible in one of the beds , in the bottom picture, is entirely self sown. We left the first lot of plants to go to seed and clearly the seed was dropped all over 2 of the grow beds. This really bolted last year and I doubt if we will leave it in the growbeds for as long this time as we will want the space for all the seedlings which are now coming up.

Di is really the gardener so I am unsure what is planned for this year. However planted seeds so far, and this is really just in the last 2 weeks, include several varieties of spinach, several types of tomatoes, various asian vegetables and other assorted bushes.
We put some spinach seedlings in during June as well and they did absolutely nothing until the last 2 weeks. In truth they didn't do nothing- most of them keeled over. However 3 or 4 survived and now thay seem to be away.

In general I feel that I have proved the concept of aquaponics as viable in this area with one major proviso- I MUST find a way of keeping the winter temperatures above the deadly lows of this winter.
I am reasonably sure that an improved version of the current heater will be worth the effort. I plan to add more insulation, longer length of poly pipe in the box, black paint on the inside of the box etc etc.
I am however also again planning a heavily insulated, partially buried glass house. Needless to say the amount of effort needed to build such a building just might scare me off- but I doubt it!!

Water heating update

Just a quick note to record the apparent success of my little heater for the fish water.
My last post detailed the construction of a very simple black polytube heater which seems to be doing the job!!!
After about 2 weeks of operation it looks like the daily addition of just 1 degree of extra heat from the unit has raised the daily minimum temps , in the fish tank, from a low of 6 or 7 to a low of almost 10 degrees now. Still not warm but I think I am finally winning.
This new heat is a bit late for all those poor little catfish but next winter things will be better!!
Yesterday the minimum was 9.6 degrees- but it was a very cold day- it actually snowed quite heavily for about 15 minutes!! At the time Di and I were working in the chook yard making a new house for the new silkies- but that is another story.

I have also added a timer switch to the big pump setup so that the water is only pumped to the growbeds between 8AM and 8PM. The reasoning here is that the growbeds cool down during the night and so will tend to chill the water passing through them.

I have also got the differential switch working and so I don't have to go down twice a day to connect the 12V pump running the water to the heater.
Needless to say all is not quite a bed of roses- the pump draws more power than one 20watt solar panel can comfortably supply and so I have added a second 20watt PV panel.
This problem should be fixed soon as I have a mini maximizer kit which I will build and install when we get back from our little holiday to Hong Kong. This kit adjusts the voltage from the panels to enable a much more efficient conversion of the power from the panel to the load.

Winter Woes

A totally gratuitous image to start this post- this was the view I had when I wandered over to the big shed this morning to check on the fish. The local kangaroos are almost tame- certainly not much bothered by us- or by the dogs provided we keep the dogs close to us.



The period since my last post have been a series of learning experiences- most of them not good.
As we are still in winter the temperatures are still low- both outside, in the shed, and much more significantly, in the fish tank water.
My reasoning for putting the fish tank in an insulated hole in the ground were based on the assumption that the water temperature would be more stable. This has been the case. I also thought that the lowest water temps would be somewhat higher than I have actually measured.
I have been recording all sorts of details including maximum and minimum temperatures in both the shed and the fish tank water.
To date the lowest room temp over the last two months or so has been just above freezing. Night time temps have often been below 3 degrees C in the shed. Daytime temps have been as high as 17 or 18 degrees. And the daily fluctuation has been as much as 15 degrees or so.
At the same time the lowest water temps have been in the 6 to 7 degrees C range with a daily variation of less than 2 degrees. So as far as variation is concerned the buried tank works.
However the stability is a bit of a two edged sword- the tank doesn't heat up much without help from me.
At the start of this adventure I chose Tandanus tandanus and Bidyanus bidyanus species as the literature suggests that they will both survive temperatures as low as 2 degrees C. Perhaps well fed adults will but little fry clearly will not.

I think I have lost ALL of the Tandanus and perhaps another 10 or 15 of the Silver perch.

The highest numbers of deaths almost always follow the coldest days.

On a positive note the fish are still eating some Daphnia which fortunately is in good supply - they refuse all other non live food. They even reject chopped earthworms which were a favorite in warmer times.

I have even contemplated growing trout next time- however that probably won't happen for another reason- the lower temps are not only bad for the fish but also for the bacteria which are responsible for changing the fish waste into plant food.

The growth of the current plants has almost stopped. I doubt if this is due to a lack of nutrients as much as simply a medium which is too cold. I reckon that in a dirt garden the soil can soak up a bit of heat from the sun and this help the plants. My plants are constantly bathed in coldish water. Perhaps I need to do some more experiments in this area.
Having said the above- all is not doom and gloom- the peas are sort of growing. And the tat soi has a bunch of pretty flowers. The tomatoes have all been removed.

And so I tried to adapt an old hot water solar panel heater to heat the water. As the solar panel has copper pipes and connections and copper is known to be toxic to fish I decided to make a heat exchange unit to transfer heat to the fish tank water without allowing the water heated in the solar panel to come into direct contact with the water in the fish tank. As the water in the heater panel would be subject to freezing I also used a glycol solution in the system. Glycol is also toxic to fish but I reasoned that the circulating water would not come in contact with the fish water so this would be OK. I made a big loop of plastic pipe to immerse in the fish tank and tried to pump the antifreeze solution around the system. Short answer - it didn't work- too much trouble getting the air out of the system etc. And the heat transfer ability of the plastic pipe is terrible. (Can't use copper for toxicity problem mentioned above, couldn't find aluminium pipe and stainless steel tube is VERY expensive).
So I have now made a much simpler heater for the water.
Basically it is 30 meters of 19mm polypipe inside the box that had held the first solar hot water heater panel. The water is simply pumped out of the fish tank through this polypipe and back into the fish tank. Crude measurements of water temp suggest that on a good sunny day, even at this time of year, I am getting a 1 degree increase in water temp during this pass through the unit. The pump I am using is a 12volt bilge pump rated at 350 litres per hour. The power for the pump is a 20Watt solar panel , a Solarex regulator and a couple of 20Ah sealed lead acid batteries. I am now trying to fix the differential heat switch which I am using in an effort to automate the process of pump on and off switching.
My current thinking is that I might be able to keep this heater going in the summer to get temperatures which should cause explosive fish growth. And perhaps even prevent the lows of this winter by "loading" up the tank and it's surrounds during the summer. Time will tell if this logic is sound or not.

To add to the problems I am having I have discovered, in the last couple of days, that the float switch which turns the big pump on and off has stopped working properly. Actually it is worse than that - it works intermittently. With a bit of luck a little adjustment to the weights and levels of the cables will fix this problem.

Cold weather

It is now officially winter where I live and it certainly feels like it. We have had a few frosts and most of the plants in the dirt garden are looking much the worst for it.
The tomatoes in the growbeds are still alive and there is still some fruit ripening on the vines. They look pretty sad as plants and I think this is probably due to some mineral deficiencies which I am attempting to remedy with blue metal crusher dust. I am told that basalt dust contains all sorts of mineral which will slowly become available to the plants. To this end I have mixed about 8 or 9 cupfulls into each growbed. Too late for these tomatoes but perhaps of use to the next crops.
Di has put in another crop of peas and they seem to be doing quite well.
This is despite overnight temps in the shed dropping to as low as 4 degrees C.
The water in the fish tank is now around the 10 degrees C mark and the fish are not eating much.

The fish are refusing everything except daphnia at the moment.
Fortunately I have found a source for good quantities of this and I collect a couple of litres of daphnia every week or so. I then put this into the spare water trough I have outside the shed and scoop out a couple of tablespoonsful daily or at least every couple of days. As it is alive this doesn't cause any problem in the fishtank if not eaten straight away. The picture is one I found on the net and looks just right. The dark "balls" inside the daphnia are eggs or the equivalent. These little critters are only a couple of millimeters long so are really just a viable food for the fish while they are at their current size of between 50 and 100mm.
On that note I have had the fish for almost 8 months and I must say I am somewhat disappointed in their growth rate. It looks like we will not be eating fish until next Autumn!! If then!!
As they are still so small it is simply amazing how much plant growth we have had. I can only assume that when the fish are almost at the harvest size that we will have riotous growth in the growbeds and will probably have to plant and harvest like crazy.


The 3rd picture shows the second
plantings of peas .
Peas were quite successful the first time around. As it is winter I expect this planting to be a bit slower to grow than last time but we will see.
Nothing quite like chomping on fresh peas straight from the bushes while doing fishkeeping chores. Enough still make it to the kitchen for stirfrys and the like.



The final picture in this post shows
some Tat soi which we are letting go to seed as Di couldn't find new seed for next time. This is an experiment and I don't know how succesful it will be but it is worth a try. And the flowers are quite pretty.
We let some coriander go to seed earlier and a few little plants have popped up in one of the other grow beds.

Insulating the growbeds

Today is Anzac day and that is traditionally the start of winter in this area.
I have been concerned for some time about how the fish will fare during the winter as it gets quite cold here in downtown Burra Creek. (Actually there is no town of Burra Creek- it is almost all ex farming land - never great farming land and now mostly hobby farms).
Already the nighttime temps are dropping below freezing outside and we have had cold enough weather to kill off the tomato plants which were growing in the dirt garden.

I had always intended to insulate the grow beds as they are above ground in the big shed and as the air temperature there is now dropping to as low as 6 or 7 degrees Celcius it is clear that the water temperatures will eventually drop as well. Current water minimums are in the 13 to 14 degree range so the tank insulation is clearly doing what it is supposed to do.

I had intended to wrap the growbeds with a product called Aircell which is a lot like heavy duty bubble wrap with a layer of heavy aluminium backed sisalation like material bonded to the bubbles. However I was quoted over $300 for a single roll which is 10 metres long by 1300mm wide. It would have been enough to wrap all the growbeds but I decided that was too much money. Instead I bought a similar sized roll of sisalation backed fibreglass batting for about $120. This was split into 3 rolls about 400mm wide and then wrapped around each growbed.
The reflective layer is fairly fragile so I then wrapped the beds with the Sisalation I took off the roof when the steel was replaced with polycarbonate.
This also had the benefit of covering over the fibreglass. This should protect the fibreglass from damage and also protect me from the batts which can cause a lot of itching.
We folded the extra Sisalation over the top lip of the growbeds . It is held to the top by a length of split 13mm poly pipe which should keep it all neat. Attaching the poly pipe was not a fun job but if it keeps the whole lot together it will have been worth the effort.

It will be very interesting to see if this part of my plan works as there will still be some heat loss from the tops of the growbeds. The next phase of the construction is the creating of a heating system for the water.

These 2 pictures were taken today. Sharp eyed viewers will notice the beans have gone from the closest growbed during the construction. Peas are the next crop to go in under the wire supports.
We have also pruned a fair bit of the tomato leaves from the plants which are still going well and with a bit of luck they will continue to produce fruit for some time yet.

Plant growth update

10ft tall tomatoes!!
Well perhaps not quite 10ft but they are much taller than I am even when I am standing on the gravel in the growbeds. In fact some seem to be trying to escape out the window at the top ridge of the shed.
The first picture shows the tomatoes about 6 weeks ago and the second , more recent picture, shows much bushier growth with runners almost to the roof! We have eaten a fair few of the fruit but there are now a bit hard to find in amongst the foliage. I plan to do a fair bit of leaf pruning fairly soon. Early fears that the flowers would not be pollinated don't seem to have come to pass and although not as prolific as I had hoped we are still getting new fruit. With a bit of luck we will continue to get tomatoes from the aquaponics setup for some time yet. In the dirt garden I expect that we are at the end of the season as the frosts are likely very soon.

Despite my earlier comments about lack of nutrients and light the vegetables have been quite productive.
We have had 2 separate batches of tat soi, several of lettuce, and good supplies of peas.
The coriander , in the picture with the beans, was a bit of a flop as it went to seed very quickly- Di reckons it was too hot at the time. Some of the other plantings also went to seed a bit quickly -perhaps for the same reasons. We also had rather slow growth with one of the lettuce varieties and the leaves were bitter so they were pulled out and fed to the chooks
We are currently getting a feed of beans about 2 or 3 times a week from about 30 plants- 10 in each grow bed- some are low as in the picture while the rest are growing on the supports I put in for the peas and tomatoes.
I have not really been a gardener before and so it is quite a thrill to be able to harvest fresh produce whenever I am in the shed.
All I need now is for the fish to produce MORE POO!
This is probably unrealistic now and I will have to wait for the warmer weather to return.

There is however the plan for a hotwater heat exchange unit for the fish- more later!!

An imagined problem and a solution?

Fish need oxygen to breath just as we do and they get it out of the water. The constant pumping of the water out of the tank and through the growbeds and back into the fish tank provides a lot of air to water contact which ensures the continuous exchange of gases.
It suddenly occurred to me a few weeks ago that if I had a pump failure for whatever reason, and I didn't know about it for some time, I only go over to feed the fish once a day, I could possibly end up with dead fish due to low dissolved oxygen in the water.
This is not really likely to be a problem at the moment due to the small size of the fish but when they are bigger it could be a very real problem. I imagine 200 plate sized fish need a fair bit of water/air contact to prevent them suffocating!
So I went looking for a big air pump- just like the ones used in aquarium setups but bigger.
It had to be at least capable of running on 12 volts and even better 12Volts and 240Volts.
I found one on eBay, bid and won, and a few days later it arrived.
I would not want to have it in a home aquarium setup because it is very large and quite noisy compared to normal aquarium pumps.
However it pumps about 40litres of air a minute and the box contains a 12Volt 7Ah sealed lead acid battery and charging circuitry etc which means that if the power fails it continues to run for some hours on battery power alone. I could also hook up a 12Volt input so that even if my inverter fails I can still keep the fish alive.
At least that is the theory!

Problems and solutions?

Although growth of the plants in the growbeds is quite vigorous they don't seem to be doing as well as I had expected.
I am reasonably convinced that I have 2 main problems:-
1. not enough light and
2. not enough nutrients.

So in an effort to solve or at lease improve on the light problem I decided to install the extra polycarbonate roofing I had bought at the beginning of the construction.
Taking advantage of a visit from my "nephew" I co-opted Gary into being a roofer's mate and we removed the zincalume roofing over the back part of the shed over the fishtank. This is a reasonably straightforward job despite the difficulty of trying to drive "one-shot" tek screws into polycarbonate sheeting whilst not putting any weight on the sheeting. Fortunately the sheeting is very strong and the occasional accidental step on it doesn't result in a crash through to the ground 4 or 5 meters below.

The fish don't seem to realise that the extra light is good for the whole system and they are currently much more skittish than they were before the extra light became available. I am hoping that they are just getting used to it and will eventually be more willing to be seen.

The not enough nutrients problem is almost certainly due to the fact that I have quite a lot of plants and not enough fish poo! There are probably over 200 fish but the biggest of them are still only about 100mm long- and a lot are much smaller.
So as mentioned in an earlier post I am adding pure Urea at the rate of 4g most days- this has lifted the nitrates to between 10 and 20ppm without causing any detectable ammonia or nitrites.
I was also adding chelated iron at the rate of about 5g per day for a couple of weeks. I was testing for iron in the water but not getting any detectable levels. However I should have been testing for the chelated iron and when I finally did so the levels were between 1 and 2 ppm. This is possibly too high a level so I am no longer adding iron. A test today suggests that the levels are a bit lower and I hope that the plants will take up more. As far as I can tell chelated iron is not toxic to fish and the fish don't seem in any way affected.

The fish are also eating less now due to cooler temperatures.
Temperatures in the shed are now a fair bit lower than they were in the middle of summer- not a surprise- as I write this the temperature outside is only 10 degrees Celcius. The tank was at about 15 degrees earlier today. The insulation I have around the tank is clearly helping to moderate temperature swings.

Unexpected Visitor

On arriving in the big shed a few days ago I was surprised to see that one of the "fish" was swimming around the perimeter at the surface really quickly.
And then I noticed that there were flashes of red from this "fish".
A closer look quickly showed that it was not a fish but a smallish red bellied black snake! I estimate this one to be about 800mm long.
Clearly it had visited the tank in search of food- The primary food for red bellied black snakes is frogs and other small reptiles.
The big shed is within 20 meters of the big dam and I have often watched red bellies hunting for prey around the edges of the water.
My first thought on seeing the snake was to quickly rescue it as I reckoned it was probably exhausted after who knows how long in the water. I have a small aquarium net taped to the end of a short piece of pipe so this was presented to the snake who immediately swam into it. I took the snake out to the bank of the dam and put it on the ground near the water .

I then realised :-
1. That I had missed a great photo opportunity and
2. That the snake might have eaten some of my fish!

I went back out to see if the snake was still where I had left it and it was- soaking up some warming sunshine. It didn't look like it had a fat belly so I doubt if any fish had been caught. It did look healthy and eventually moved off into longer grass to hide from me.

The fish were a bit skittish for a few days but eventually returned to normal and I although I have no way of counting them it looks as if I still have as many as I had before the visit.
I must come clean and admit that these pictures are not of the snake in this post- I prepared these images earlier. It is one of the snakes which live near the dam which I had photographed some years before.

Top up water

As the growbeds are not fully planted, and the area is really a glasshouse, a fair bit of water evaporates each day. The growbeds get quite hot to touch in the middle of the day which clearly accentuates the problem. .
To keep the system running well and to ensure the plants get adequate water top up water is needed fairly often- really about every couple of days. The plan is to fill the growbeds to within a couple of centimetres of the top of the gravel each flood cycle.
I have a 20000 litre rainwater tank collecting the water from the shed and I have run a pipe from that tank to just over the fish tank.
Up until the addition of the top up barrel I simply opened the big white gate valve and ran in water for a short while. The problem with that arrangement was that I didn't know how much water I was adding and more importantly on one occasion I forgot the water was running for about 10 minutes and ended up adding far too much. I didn't overflow the fish tank but I did have to reset the float switch which was a pain.
So I have added a 200 litre blue barrel which has a sight tube which enables me to add, and record, an accurate volume of water when needed. At this stage it looks like I need 50 litres every second day. I doubt that I will need to add anything like this much in the cooler months but it is still likely that the extra water needed over a year could be as much as 7000 to 9000 litres. We have had a fairly wet last couple of months and the 20000 litre tank is still full so that much water will not be problem. Posts to several of the online aquaponics groups suggest that an aquaponics setup uses only about 10% of the water of a dirt garden. I have no idea if that is true but I do know that we had real trouble with enough water for our dirt garden the last couple of years wheras we look like having no trouble with water with this new venture.

Azolla production

I have been reading all sorts of good things about the food value, for fish, of the water fern azolla. It contains quite a lot of protein in the dried state and has been used in lots of places around the world as a protein supplement in livestock production. The most interesting thing about azolla is that it can double its mass every few days when provided with the right conditions. I had a few failures in trying to get a culture going but am now producing quite respectable quantities on a daily basis. This is scooped out of the pond and dried on a rack which is simply flyscreen over a bit of steel mesh. After a day or so of drying I rub it through a sieve and now have about 9 or 10 litres of dried leaf. As the water content of the living plant is about 95% the 10 litres of dried leaf represents probably 200 litres of fresh azolla. And that was all produced in the 1200 litre stock trough outside the shed over about a month or so. This little plant grows like a weed when given the right conditions.
To start the culture the trough was half filled with water and a couple of biscuits of hay and a handful of super phosphate was added. This creates an algal bloom which was actually planned as a starter food source for mosquito wrigglers and daphnia. I got quite a few feeds of wrigglers and daphnia for the fish but then in a moment of weakness chucked in a few handfuls of azolla. The water in the trough became so covered with azolla that I no longer get a harvest of live food for the fish.

So I have now created a new area where I can grow azolla and this will free up the big trough for live food production. The dried leaf will become one of the ingredients of my homemade fish food - more about that later.

The new area is made up of 6 half blue barrels each of 100 litres - the total volume is about 600 litres and the total surface area is about 3 square metres. These have been seeded with hay and/or super and should be going green within a few days . I plan to start adding chicken litter and droppings in the new areas as an experiment. The overall plan is for as many of the inputs to the system to be home grown- sort of a permaculture system where one areas waste is another areas nutrient.

The pieces of shadecloth in the water are there to give lizards, which seem to want to get into the barrels all the time, something to climb out on. Before the shadecloth went in I inadvertently trapped several of the Cunninghams skinks which live near the shed. Fortunately the water was not deep enough at the time to drown them and they survived.

More fish

A couple of days ago I received a delivery of 100 Silver Perch fingerlings . These were part of the original plan but were not available until last week.
They came from
Ian Charles at
Silverwater Native Fish , Old Wagga Rd, Grong Grong NSW 2652 ph (02) 69562122.

A really nice bloke to deal with. I had a chat with him as he was delivering live plate size Silver perch to a Chinese restaurant in Jamison. He transports the big fish in a heavily insulated box with a pure oxygen bubbler. The fish are partially anaesthetised by adding a small amount of clove oil to the water. He had about 90 fish weighing between 600g and 1 kilo in a 400litre box- all quite happy - but very crowded.

My fish were a lot smaller- between 40mm and 80mm. Unfortunately about 20 died in the first couple of days but the deaths have stopped and the fish now look fat and healthy.
They spend most of their time in the middle water unlike the cats which are mostly on the bottom. Like the cats they are very fond of chopped earthworms and when feeding seem to encourage the cats to move higher up in the water. The cats will have to eat faster if they are to get their share of the worms. Worms are a treat- the primary food at this stage is a sinking pellet food which although Australian made is made from imported fish meal so I plan on making my own fish food in the not to distant future.
I suspect that the silvers will grow a fair bit faster than the cats so we might be having fish dinners late this year with a bit of luck.

A progress report Jan 08

It is now mid January 2008 and the system is working well.
We have had quite a few feeds of sugar snap peas, Tat soi, lettuce and pakchoi.
In fact the first crop of tat soi has all been consumed and a second crop is now on the way as you can see from the picture on the right. The sugar snap peas don't look great but they are still producing a few pods. We will soon be cutting off the plants- planning to leave the roots in the gravel so that they will release the fixed nitrogen back into the system.
Having a little bit of leaf eating grub problems- probably the white cabbage moth- not a major problem yet so I don't think we need to do anything drastic. Any grubs I see will become fish food and that is really just extra protein.

The fish are growing a bit slower than I had expected- now perhaps 60-80mm long and looking very healthy. I have even worked out how to catch some for photo sessions. Used a yabby trap which was simply left on the bottom for a day or so for the fish to become accustomed to it . I then dropped what has become a preferred food- chopped earthworms- into the trap which I lifted quickly out of the water. Caught about 20 or so very vigorous little catties. They now look more like fish than tadpoles. Not hard to see why they are called catfish with those whiskers!

I had thought that I might have had a problem with nitrate levels and this has turned out to be the case. However I was a bit worried that the levels would be too high whereas in fact the level had dropped to almost nil. This would not be a problem if I had a population of large fish. However my fish are very small and the growbeds are quite large and so the fish poo seems to be unable to keep up with the plant's demand for Nitrogen. So I have started adding extra Nitrogen in the form of urea. I bought a box of pure urea from a garden supply centre and have begun to add 4g per day to the fish tank. Apparently fish don't produce urea as most other animals do when they need to excrete Nitrogen. Fish produce ammonia. Fortunately it looks like urea is much less toxic to fish than ammonia and so far this seems to be the case with my fish. I decided on 4 g per day on the basis of it being 1 ppm for the 4000 litres of water. I am assuming the biofilm is converting the urea to ammonia which is then being converted to nitrite and nitrates in the usual way. After a week of adding 4g per day I now have lifted the nitrate level back to about 10ppm while the ammonia level is still Nil.

Despite the potentially low Nitrogen levels the tomatoes planted in November have finally flowered and have begun to set fruit. Still only the size of marbles but I reckon the extra N will get them away and we should be able to start picking tomatoes within a couple of weeks.
This is very exciting as the original plan really was to ensure a tomato crop after the problems we have had in the last couple of drought years in the dirt gardens.
The last picture shows the dozen or so tomato plants. Note the runts on the left of the picture. These were moved just after germination and this was clearly not a good idea. We successfully transplanted tat soi plants but it was probably too much strain for the tomatoes. I will leave the runts in the growbed just to see what happens.
With a bit of luck we might get a late crop.