Aquaponics - Silver Perch

I just spent a very pleasant 45 mins watching (and patting) my silver perch eat duckweed. 

I took some video but ran out of arms to do everything (lighting, camera, patting) so tomorrow I'll get someone to help and get some decent footage.

I know this doesn't really qualify as worthy of you taking the time to read it, but I was pretty excited, so have to bang on about it to someone. And Mrs 120 Things in 20 years is already asleep. 

Aquaponics - Silver perch feast

I cant remember if I even mentioned this because I was probably in some kind of deranged pain killer broken rib induced state when it happened, but I may have forgotten to mention I ate one of my big silver perch.

It looked like this.

The South Australian Fisheries people suggest the most humane way (and best way to protect it's eating qualities) to dispatch a fish is to plunge it into an ice water slurry, and leave it there.

A few hours later I scaled and cleaned it, and lightly salted it inside and out.




I wrapped it in whatever you call thin plastic kitchen wrap where you live, and left it in the fridge for twelve hours, then cooked it whole.

It was one of the nicest fish I have ever eaten.

Crazy fat.

You cant really tell from this angle, but it was in very fat condition. Looking down from the top, it had that thick section just before it's tail like a dolphin.

Most wild caught fish don't seem to have that.

I'm guessing it's because life is a little tougher in the wild when you don't have an unlimited amount of feed available.

Anyway...

This fish was in very good condition and had excellent fat content.

Apparently silver perch fat is high in Omega 3, but it was mostly delicious.

It weighed 1.08kg gutted and scaled and was 33 cm long.

I wish I had built a much bigger system ages ago so I could have a lot more.

Successfully farming your own protein in only a couple of cubic meters or space is an amazing thing to be able to do in suburbia.

I totally recommend it.



120 Things in 20 years totally recommends it.

Aquaponics - Silver Perch

It's been a while since I paid any attention to my Aquaponics system, but it was nice to find my Silver Perch have been busy growing.

I wandered out to the Aquaponics system for the first time in ages because it was making a slightly different sound, and it turned out to be a partial blockage of the pipe work.

Blocked with tomato roots.

I've been expecting some problems because when I pruned back the four tomato plants that are still growing from last year, I accidentally killed one by snapping it off at the base. The roots are all meshed together with it's three tomato plant buddies, so there was no way to get them out. I figured it would work it's way out in the end. It probably would have. The system was still working, with some water going through my overflow. The overflow exits from the surface of the fish tank water, where in normal operation, the water exits from the bottom via a solids lifting overflow. As a result it's unlikely that both would be blocked at the same time.

Anyway, everything seems to be ticking along nicely.

I don't really know how big this fish is (I'd guess around 40+cm), but it's in really good condition. They're not just long, but really heavy as well. Heavy looking that is. I wouldn't like to try to catch one, I think it would be a little disruptive.

I'm not sure if this is the bigger of the two, but one of them now looks like this...

Aquaponics - Silver Perch update

I recently ran out of fish feed, so I've been hand feeding them worms, and what ever they call fly larvae in whatever part of the world you live.  They are called "gents" here when bought as bait, or stored in a fridge shared with people who don't want maggots in their fridge. "Maggots" when found in smelly stuff.

The point is, as a result of feeding them live food like worms, gents, and caterpillars, they are venturing a bit further up the water column to the point where they are now easy to photograph.

This guy is pretty big.

And heavy looking.

It looks like this up close.

I have no idea how big or how heavy it is, but I'll try to get a photo next to a ruler.

I wont try to weigh it because I cant think of a way to do it without stressing it.

I'll weigh it if I ever eat it.



120 Things in 20 years - Sometimes your aquaponics silver perch get quite big when you're not looking.

Electronics - Aquaponics - Demand fish feeder software

As far as I know, the software is all working on my demand fish feeder.

It's a bit of a mess, with a few goto statements and a few unused variables. I'll fix it in time, but for now I'm going to move onto getting a finished product up and running. As far as I can tell with the software simulator everything works, but the real world might be a completely different story. (the breadboard version also works)








A switch lever extends down into the water. If a light near the lever is lit, the fish can press the lever and feed is delivered. Feed can also be offered with an override button that sets the light on and the feed on if the fish hit the lever (so you can show people how it works)

Dawn detection seems to work. In the end I went with two startup options.

1. A human who holds down the FeedNow override button during startup, then taps out the approximate number of hours since dawn. This skips the code that searches for a new dawn.

2. An abnormal restart with no human. This stops all feeding (there might have been a blackout, and subsequent ammonia buildup) (note to self - add code that flashes some lights to indicate the device is in abnormal start mode so a human can reboot it if they desire). Feeding resumes after night time is detected, and a dawn is detected.

The user can select (via a screwdriver to resist little finger making their own adjustments) ...

 - the feed amount per day in tenths of a second of motor on - from 0 to 65 (I'm guessing I'll use 1/2 a second per feed event) The motor turns an auger under a hopper full of feed. So there is another adjustment available

- The number of feeds in a day that are offered (0 - 255 per day)

- The level of light at which dawn is detected. This allows for a system built in the glow of a streetlight or whatever. At dawn each day, all the numbers reset. This is a bit of a problem as far as reading how many feeds were delivered in a day, but for now I'll leave it as it is. My fish feed like crazy at dawn, so I want to give them the greatest opportunity to feed. Eventually I'll add a data logger, so it wont matter when it resets.


The system reports...

- the number of hours since dawn

- the number of feeds since dawn

- The number of false hits to the feed lever when the FeedIsAvailableLED is NOT lit (these will go down to near zero once the fish learn they can only get food when the light is on)


I ran out of feed a while back, and have been feeding my two big silvers on duckweed, lettuce, and worms, so I will need some pellet food before I can test it in the real world. (I still have the PVC device from the first version).

I'll also need a motor as my original one is no longer with us.

The feeding regimen isn't very intelligent at the moment, but I'll do a bit of research, and add some code that tries to deliver the maximum amount of feed in a day that the system can handle. This will probably involve allowing 3/4 of the feed to be dumped at will, with the rest being spaced out over the day ... or something. I haven't given it enough thought because I don't really know what the fish need. My experience in fishing for wild fish indicates that the feeding pattern is far from a constant grazing all day long. I'll work it out.

But...

It's going to work. In fact, it already does.


120 Things in 20 years That's all. Just 120 Things in 20 years.

Aquaponics - Fish stocking density

So...

1 fish @ 500g per 20L of filtration, or 2.5% of the media in fishmeat by volume (fish being neutrally buoyant equal water weight by volume  (1 ml of water = 1g) seems like a reasonably common stocking level.

...

So for every 20 L of growbed media (gravel, clay balls etc) you can stock 1 fish that you intend to grow out to plate size.

Plate size is considered to be 500g, and reflects what a restaurant might like to serve a customer on a plate rather than the actual size of your plate.

I dont know what size your plate is.

Although it's probably, by coincidence, roughly the same length as a "plate sized fish" wide.

Or high.

Anyway...

So a fish, that looks nice on a dinner plate, is around 30cm long, weighs around 500g, or a little over a pound,  and requires around 20L or 5 ¼ gallons of filtration or grow media to support it throughout it's life of pumping fish crud into the water.

“Stop eating so much. You don't need that much protein in one meal.” I sometimes tell myself. But I'm wrong. Fish is delicious, so I'm probably going to keep eating that much.

So you put a stack of fish into your system, and you end up waiting quite a while, then you pull them all out, and put them in the freezer.

But fresh is best.

Why don't we eat smaller fish? Fish are crazy brave when they are young, and feed like mad taking all kinds of risks to get to the food before their fellow fishies.  This means they grow quite quickly when they are young.

Trout and barramundi seem to grow to plate size in 8 months. But that might be because they are already quite grown up when you get them. Silver perch take around  two years. Or actually two summers, as they dont feed a lot during winter. Most fish varieties grow quite fast at their preferred temperature.

So if our systems need the number of fish they can support to give the vegies their best conditions to impress, why do we have so few fish for so long.

Most people stock a number of fish that their system can cope with once they have grown to plate size. But that means the system is low on nutrients for the greater part of a year, and then perhaps overloaded for a bit, then suddenly, has no nutrients for the plants at all when the fish are all harvested.

The system's resident veggies must hate it.

But what this means is that you either have to supplement your ammonia, or nitrate inputs into the system with Charlie Carp (fishy goo) or something to keep the plants happy.

So, all that stuff is true.

But its also true that we eat fish that are smaller then a plate sized trout. Sometimes a lot smaller.

In South Australia, where I happen to be, we eat Australian Herring, Gar Fish, Leather Jacket, Yellow Fin Whiting, and almost every other fish we eat can be bought or legally caught at smaller than plate size. I think even our King Gorge Whiting, considered by many as one of the greats, are legally caught at less that “plate size”.

So what's so good about plate size?

Don't answer that, it's a rhetorical question. Unless there is actually an answer...

then …

go for it.

But...

Ideally we should stock our systems with 100% of their fish meat holding capacity, and start eating the biggest of the small fish the following week.

That could get a little finicky when trying to fillet a 4cm fingerling, but perhaps there is some kind of compromise.

Silver perch take two summers to reach plate size.

Perhaps we should stock an amount of silver perch, such that after one summer, there is enough fish by weight, that we are not over stocked, but that we can start eating. They grow slowly in the colder time, but that might mean we can slowly eat some in an attempt to keep the stocking level at close to optimum, and when the next summer comes, we still have the right amount of fish, but we can start eating more, more often, until we find ourselves with one last megafish, still capable of running the system.

Obviously rather than one mega fish, it would be better to buy more fry at a time when the system could afford ...say... 50 new fish, if there was one less big one in the system.

That should be the trigger for buying new fish.

After working out how many fish such a program would require to restock, approximate the big fish equivalent to the number of new fry, and restock when eating the big fish would allow enough filtration media, to buy a new batch of small fish.

This might seem obvious to some, but it doesn't seem to be normal practice.

Given the price of decent quality, ethically raised, organic, un-polluted, un-heavy metalled, fish, and the feed conversion rate of around 1:1.2 (ie 1.2 kg of feed makes around 1kg of fish (insects, algae etc make up some feed, and fish do a whole lot of floating perfectly still waiting for food to wander past them, so they are fantastically efficient(some trials have shown better than a 1:1 ratio))) …

where was I...

Given all that, and the fact that you pay a bit for your new little fish (around $1.80 for me) it still works out to be an exxcellent deal to eat the fish way before they are plate sized.

So...

I think I should try to work out how many fish I should buy to make this form of stocking a reality.




120 Things in 20 years needs to make a spreadsheet to work out a better aquaponics fish stocking density plan. Or just take a bit of an educated guess.

Aquaponics - Two year old silver perch

Trying to measure a fish without disturbing it turns out to be a very tricky thing.

Eventual I managed by taking some video and then grabbing a single frame from it to turn into a happy snap.

Even then it's difficult to make out.

I think it's around 275mm long.

That's it's tail extending back a little behind the ruler.

They are roughly two years old, and I'm guessing it would weigh around 350 g.

It's not a lot, but still not bad considering how often they went without food during all the problems I had with poisoning them etc.

I suspect I could have seen double that weight if I had fed them as much as they wanted all the time. So I think it's time I got the demand fish feeder working. There hasn't been much point over winter as they don't do a lot of eating, but spring is in the air, and I want to get some more fish. It's also about time I did something about completing the fish feeder project.

I seem to be half doing way too much stuff of late.



120 Things in 20 years - If an aquaponics task is worth doing, and to get to the end of a task you must pass through the middle, then it must be worth half doing.

Aquaponics - Silver Silver Perch

My silver perch are going silver.

I'm not really sure what that means.

Perhaps it's a sign that I should eat them and get some trout for winter.

Pictured here in this very poorly composed photo, is my bigger angry one.

The smaller one is hiding.

I made the smaller one a small hide from a sliced down length of 90mm PVC so the ceiling is too low for the big one to enter. It seems to have created at least a bit of peace in the system.


One slightly interesting thing of note, is that the overall calm in the tank rises considerably at night.

More and more, I'm convinced that the angry fish is being a bully because it's scared. Perhaps if you feel a predator is near, chasing a smaller fish out into the open is a good way to distract the predator from eating you, because it becomes too busy munching on your old buddy that you've know since delivery day in the plastic bag.

We can all learn something from that.




120 Things in 20 years teaches us that not only do Silver Perch sometimes turn silver, but that if you think a lion is going to attack you, it pays to help a tourist to the front so they can get a better look.

Aquaponics - My angry silver perch

My angry silver perch just got angry again.





At 120 Things in 20 years, being angry just draws attention to yourself, and leads to pan frying.

Aquaponics - Healthy silver perch feeding

It seems my fish have totally recovered from whatever it was that was troubling them, and are now growing so fast that I think it's time to eat another.

Since I lost a few a while back to some mystery problem, the remaining six have been getting more food each. And one in particular is getting much more than the others just because it's the biggest.

Eating more than your share is normally an excellent tactic for success in the wild, but in my little system, it just draws attention to yourself, and makes you stand out as a likely candidate for the plate.

They are now looking around for more food than I can give the system.

In aquaponics, it's important to fed the system rather than the fish. If you keep feeding the fish as much as they want, when they get bigger, there may come a point where the system cant process the amount of feed you are putting in. So always thinking in terms of feeding the system rather than feeding the fish is a good idea.

All you need to do is keep checking your water with a test kit until you start to see the first signs of it being overwhelmed. If you start seeing ammonia or nitrites, it means you have reached your systems limit. take note of how much feed you are putting in and then back off just a little to be sure.

Then never feed your fish more than this amount in a day.

If the fish want more feed than you can give them, it's time to eat some, or sell some if you are growing a variety not for the plate.

My fish look like this at the moment, with the biggest being around 25 cm in length.






120 Things in 20 years, where the greediest of your Aquaponics - Healthy silver perch feeding, tend to be the first to hit the BBQ.

Aquaponics - Sad fish

Whatever it is I did wrong, I did it well.

I have some sad looking fish in my aquaponics system.

The nitrite readings are back to zero as are the ammonia readings, but the aftermath lingers on.

Most of the fish have some degree of scale damage.

And some have what looks like ulcers. I'm hoping it might have been because they were itching against sharp things because the nitrites were acting as a skin irritant, but I don't really know.











The temperatures were high over the last couple of days, and the water temperature got up to around 28 or 29c. That's pretty high water temperatures, even for an Australian native fish.

There were a lot of bugs like dragon flies around the water as I had the door to the grow house open, so It's possible the fish got a lot of natural feed that I didn't know about.

Also I've found a few ants having a bit of a swim in the system.

I found a rotting bok choy, and a rotting bean plant, that may have been contributing to the ammonia load.

Any one of these things, or all of them together may have contributed to the ammonia and nitrite spike, but I suspect I might have accidentally filled their feed jar a second time. Often they haven't eaten their maximum allotment of feed for the day, so the next day I fill the jar to the limit the system can process, and then feed them as much of that as they want over the day. But it's possible I fed them the remainder of the jar in the morning, then refilled it.

All the more reason to get this demand feeder off the bench and into the system.

Aquaponics - Silver perch eating lettuce

I finally managed to get some video of my fish eating lettuce.

I left the camera running for hours and eventually got a few hits. They seem to eat a lot of it overnight, but hardly touch it during the day. Perhaps it draws too much attention to themselves.

Here is all the feeding I managed to capture from all those hours of footage. The first scene doesn't really catch them feeding, but I like it so I left it in. There was a lot of footage where they spent time hanging around under the lettuce as they did in the first scene. Perhaps the water tastes nice under the lettuce.

Aquaponics - Fish salad

A fish salad doesn't need to involve eating a fish. Sometimes its enough to just invite a fish to a salad dinner.

Some of my cos lettuce is going to seed, and that means it starts to get a bit bitter.

We repeat harvest our cos lettuce by pulling off leaves as we need them. This means you need a lot less room to get a salad every day, because the root stock is big and healthy, and the leaves you pull off are soon replaced. Repeat harvesting means none of the waiting for all that growing plants need to do when you plant them from seed.

But one nice thing about keeping silver perch, is that they eat all kinds of stuff.

I cut the top off a lettuce and dropped it into the fish tank.

Usually, you don't see any great excitement from the fish, but by the next morning it looks like it's been attacked by a bunch of lazy vegetarian piranha.

Aquaponics - Fish death

It's horrible when you lose livestock. It's even more horrible when you have no idea why.

I found this guy on the concrete. Not such a good place for a fish.

It doesn't look like it was dragged out by a cat or anything. And, in fact, looks in pretty good condition.

Apart from being dead.






The day before the fish death, I added a small pinch of potassium bicarbonate to my system to see if it was a lack that was causing my baby spinach to yellow.

Food grade potassium bicarbonate is an additive that people growing aquaponically have been using for  ages. It's used as a supplement if there are insufficiencies in the fish feed. It's also considered safe to add to your system in the doses I used.

I find adding anything to my system to be a really scary pastime, and would prefer not to ever add anything. In this case it changed the surface tension of the water slightly, and created bubbles.

The bubbles collected around the pipes and looked a little like the bubbles you see on the surface when fish are distressed.

A little like those bubbles but not quite the same. These were slightly looser and bigger than the ones I saw during my fish from the poison bush.

But similar enough to make me uneasy, especially when the next day I notice that one of my fish is missing.



I still have no idea what the problem was, and I'm told the bubbles are normal when you add potassium bicarbonate.

It's possible that the fish just had some other issue.

All the others look as happy as they always have.

I have no idea what caused it, and given the level of the expertise of the people recommending I add potassium bicarbonate, I doubt it had anything to do with it.

I hate coincidence.

And problems I don't know enough about to solve.








And then there were ten.






.

Aquaponics - Worms

Worms.

I bought some worms and fed them to my fish.

They went nuts for them.

My worms came in a tub that said there were 70 of them inside. It also said they were from a company called Orana Inc.  The package didnt mention what kind of worms they were so I looked up their website.

Worms have web sites these days.

It turns out these people help other people who need help, and help them help me get worms. That's a lot of help, so all things being equal, and you live in Adelaide, (which you don't) buy worms from these people.

It also turns out my worms are known as red wrigglers. I bought them from a fishing tackle store as bait worms, but it looks like they may be the same worms you might add to a composting worm farm.

Someone named chillidude suggested that silver perch might not lose interest in food over winter, but instead, might just have different food requirements. I thought I'd give it a go, so bought some worms.

I did a bit of study on worms and found they can happily live in an aquaponics system. It seems, as long as there is plenty of oxygen, they can deal with being under water for ages.

A lot of people add worms to their systems, but quite a lot find that worms have moved in of their own accord, so it must be a nice place for them to live.

I added some worms to my system.

They help break down solids like roots, that are left behind when you harvest or remove a plant. They also help break down fish solids and make sure all the solids are spread throughout the grow bed rather than all gugging around the point or points where the water enters.

I added my worms in the corner opposite my core sampler, in the hope that I will find some in a core sample one day, and gain some idea of how long it took for them to get there.

It took less than 24 hours.

This isn't a picture of it taking less than 24 hours. Its a picture of the other corner.

The corner where I added the worms.

I like my core sampler.

This isn't a picture of the core sampler, but is in fact the opposite corner where I added the worms.

Its taken a few minutes after I added the worms.

I like my new worm friends.

These are some of my new worm friends.











I don't see them often, but I know they care.

.

Aquaponics - Silver perch scale damage

My fish went on some kind of crazy bender last night. It's as if they threw a party I wasn't invited to.

The tank was trashed with the thermometer flung casually in the middle instead of hanging neatly on the side, the half terracotta pot I recently renovated for a hide was on a crazy angle, and no longer sitting on it's side. Someone had even thrown the TV out of the window*.



The medium sized guy that in the video spends quite a bit of time sitting second from the right, seems to have come off a bit worse than the others. He looks like he tried to scale himself. Some of the others have some dents and bruises as well.

It's left me with with a decision to make, because they almost certainly injured themselves on my terracotta pot.

If they got harassed by a cat or something, they need the cover as it may well have saved them, but if they just went on a bender and ran amok for a bit, I should probably remove the terracotta pot for their own protection.

It's also possible that they are outgrowing the pot and I need a bit of a rethink. It could even be the fact that I knocked out the base to make a tunnel rather than a cave. This allows them to swim right through it. Perhaps some are swimming through too fast. A cave shape might force them to enter a bit more gently, or reverse in or something.


*TV story is a likely reconstruction, and may not have occurred exactly as depicted

Aquaponics - Safe fish hides

I've been very lucky since being unlucky.

The first fish deaths I had over the first months after cycling my aquaponics system, turned out to be caused by a plant that seems to be only poisonousness to fish.

Since then, I haven't had any more deaths, but it occurs to me that it might be possible for a fish to die, and I might never notice. Or at least not notice before it began to decompose and foul my water.

The eleven silver perch spend most of their day hiding from imaginary predators in the halved terracotta pot I put in the water for precisely this purpose.

You can never be too safe from imaginary predators.

But if and when I make a bigger system, I think I'll make some fish hides in such a way, so that if a fish dies or is sick, it cant just get all sleepy in the hide on the bottom.


I suspect the easiest way to do this would be to suspend the hide a little way off the bottom, of even high up near the surface. That way if anything dies or is struggling, it will be obvious, on the bottom rather than hidden from view.

As a temporary measure, I've cut the base out of my terracotta pot using my preferred precision tool,(hammer) so it's now a tunnel. The powerhead is pushing flow directly into the hide so if anyone gets sleepy, they will get pushed out the back, and should become visible.

I'm not expecting to lose a fish, but simply had the thought because of hearing about someone else's problems.

Aquaponics - The state of the fishies

Happy birthday 120 things in 20 years!

I was looking through my youtube videos and was quite surprised to see how much my fish had grown. I forgot how small they were when I first got them.

They now look like this. The largest is probably around 22 cm long. The water temperature is only 10 degrees c in the morning because of overnight heat loss, (it's winter in this part of the world) but I'm running a powerhead (a powerhead is a fishtank water moving device that acts more like an outboard motor than a pump) to keep the water moving. This seems to be making them more active, and they are eating much more than I would expect.

Normally silver perch shut down at around 16 degrees c and eat only a tiny amount until water temperatures improve.

They seem to love the high flow rate and actively seek it out, even though there are calm areas in the fish tank.  The following video is in 10 degree c water.

They used to look like this!

Aquaponics - Silver Perch feeding dynamics

I've got to get hold of a better camera.

I was taking some photo's of my fish, and thinking of doing a post on their growth rate over the last 6 months, when I noticed the way they absorb a feed pellet.

It is quite interesting.

For some time now, as the fish have become bigger, I've been hearing a violent "thuck" sound as the fish take feed pellets off the surface of the water.

I was never sure if it was their tails simply making a splash, or something else.

But this seems to indicate they might be sucking in a stack of water with the pellet.

What ever is going on, it's making me think it might be worth revisiting with a better camera.

This series of shots spanned just 1/5 of a second.

Aquaponics - Silver perch underwater

A front loading washing machine makes fish more visible.

I salvaged the door from a broken front loading washing machine, and suspended it over my fish with the camera sitting inside it. Camera washing machine goggles allow me to see my silver perch underwater. After seeing the results and being able to see the underwater component of my aquaponics test system, I'll definitely be incorporating some kind of porthole into the lager system.

I turned on the powerhead, and pointed the camera where the current was strongest. The fish seemed to love the strong current and spent much of their time in the full strength, rather than taking cover behind the pump at the other end of the tank where it was relatively calm.



While I had the camera outside I thought I'd try to measure my fish. I dropped a 10 cm length of plastic pipe into the fish tank so as to get some idea of their growth rates. And after photographing the school next to the pipe, was surprised to find I actually had eleven. I thought I had nine.

The smallest is still only around 7.5cm and the largest is around 15cm.

I think they might have been much larger if not for the stress they were put under from the poison plant, and the fact that whenever I lost a fish, I would stop feeding them for a day or two, then feed them only a little for the next week. It's standard practice to stop feeding the fish when anything goes wrong in your aquaponics system to ensure there is no extra pressure put on the fish from nitrite or ammonia spikes. Often a fish death can increase your levels of ammonia and nitrite to dangerous levels, so feeding the fish can just add to your woes. It doesn't harm the fish, and potentially can be of great benefit.