Aquaponics - Selective yabby breeding

I still have my yabby brood in a small aquarium sitting on my desk. As I type I'm watching them going all crazy for some fish food flakes.

Some are much, much bigger than others. Originally the difference was only 10% or so, but now some are three times the size or more than the smallest.

I get the feeling that people would always selectively breed from the fastest growing yabbies so that they might get a more productive farm over a few generations, but studying their behaviour up close like I am, I'm starting to wonder if that might be a bad idea.

The big ones are always the aggressive ones.

No doubt they got that way because they are getting more than their fair share of the food supply, and perhaps by eating one or two of their brothers and sisters along the way.

Perhaps that's not a good way to run a farm. Where some of your cows are eating the others, or at least stealing all their food.

One of my batch of yabbies seems to not be part of any of this. It's on the large side of medium in size, and seems to spend most of it's time grazing algae from the surface of a sheet of gutter guard (plastic mesh to keep leaves out of your house gutters). Mostly it's left alone, and more often than not leaves others alone when they occasionally venture onto it's bit of turf.

I think this kind of beast might be a better candidate to breed from.

Not quite as big, but a lot more sociable and a bit less cannibalism.

And who knows, perhaps without the aggressive ones, this type would be just as big.

I'm going to try to find out.



120 Things in 20 years went to a lousy seafood restaurant, but now wants to eat more crustaceans.

Aquaponics - Yabby stocking density

I've been thinking about stocking density, and it isn't even close to the holiday season.

I've had a clutch of baby yabbies (freshwater crayfish like things) drop from their mother, and for the last week or two I've been watching their behaviour through the glass of their small aquarium.

They spend most of their time running the boundary and bumping into each other for a quick fight, then moving on.

The result of all this watching is that I've had an idea.

The popular numbers I hear for yabby stocking density are that you need one square metre of lake per adult yabby if you want to farm them to eat (and have them grow to a decent size), but I think that might not necessarily be the case. I think that perhaps you need a linear distance of boundary per yabby rather than an area.

I have a feeling that in a lake, the yabbies might also run the boundary, bump into each other, and fight for a bit before moving on. This would mean that a large normal shaped lake might hold less yabbies than a long thin lake that took up the same area. I'm trying to stop them fighting and to give them the illusion of having a decent patch of lake to call their own, so maybe, the longer the boundary, the more yabbies you can keep.

Maybe.

If this turns out to be true, a long thin lake with a series of baffles might prove to be the better bet.

Or not.

Who knows.








If it works I hope it makes a stack of yabby farmers a stack of money, or helps someone who depends on their yabby farm to eat eat a bit more, or perhaps it could help someone like me to grow some yabbies in their aquaponics system.

Who knows.



120 things in 20 years doesn't know.

Aquaponics - Yabbies!

I just raised some baby yabbies. Yabbies are a freshwater crayfish that call Australia home.

Which is nice.

So now I have to farm them.

Tricky.

Yabbies are so delicious that they tend to eat each other.

Yum!

Tricky.

The problem is they they each want a stack of space to call their own.

They also take their time growing, but I just found this from...

http://www.fish.wa.gov.au/Documents/aquaculture_yabbies/how_to_grow_bigger_yabbies.pdf

"Separating males and females by hand is time-consuming and prone to mistakes. To make this
easier and more accurate, a hybrid has been discovered that only produces male progeny (by
crossing male WA yabbies Cherax albidus with female Cherax rotundus yabbies from NSW)"

According to the Western Australian Government fishy people, "Monosex culture provides a 70 per cent increase in gross return to the farmer."

I've had my first batch of yabbies drop from their mother, so I'm now a little obsessed with high stocking rates. I have the entire clutch in a very small 30 litre tank. So far they don't seem to be hurting each other, but they are very vulnerable when they shed their crunchy outer shell to make room for the next bit of growing they plan on doing. Shedding your armour also turns your pincers into mushy things that are no good for pincing.

No good at all.

I put the berried (that's what we yabby farmers call yabbies with eggs stuck to their undersides) female in a cage made of gutter guard (a plastic mesh to keep leaves out of your house's gutters) so the delicious babies would fall through and wouldn't get eaten by their mum. It seemed to work. Babies would let go, spend a minute or so near their mother, then drop to the bottom and never return.

For high density raising, I have a bit of a moral problem with battery hen style conditions even though (or perhaps because) I did some work on a design a few years back. But now I have an idea that I think might work for an IBC.

Basically its a 3D zig-zag of shade cloth that works it's way down a container like a staircase...kind of, so that there is a minimum of 5cm and a maximum of 8cm between each level. I'll attach a stack of PVC homes on each level that get larger and fewer as they get to the top. All of them should point downhill a bit so food and waste don't get stuck, and the basic plan is that the bigger you are, the higher you rise in the yabby high-rise (with me being at the very top). There would be gaps around the edges, so the smaller yabbies and babies would be able to find their way down with ease. They can sort it out among themselves as to who gets the housing at the top nearest the biggest food.

Watching my adult yabbies, I see that when they eat they let a lot drop. They leave a lot of crumbs. They make Cookie Monster look like something best described with words like "refined". They are also bottom feeders, and are not opposed to eating a meal that has already made its way through somebody else's digestive tract. Or more than one somebody's digestive tract.

So my hope is that I can add fish feed, or even veggie scraps (yabbies aren't fussy) into the top, and draw nutrient rich waste water that has been munched into very fine particles from the bottom to add to my growbed.


120 Things in 20 years needs to learn stuff. It's been a while.

Aquaponics - Fish

Aquaponics - Fish

Fish! Vegetarians, this page might not be for you.

The swimmy, tasty side of the aquaponics equation is fish. Depending on where you live there are a few different options. Talapia might be one if you don't live in Australia. Statistically you don't live in Australia. If you did live in Australia, and you grew talapia, you might get into a stack of trouble. Talapia are a pest species for all of the reasons that make them a good candidate for aquaponics.

Catfish. I know nothing about catfish but it seems like they are a candidate for aquaponics. Other species that might be worth a look are Cod (angry, eat their young), Barramundi (warm water), Jade perch (highest omega three), Goldfish (only swallowed whole by 50's youth in TV sitcom "Happy Days") and various things like clams, and walking things with claws(whatever they may be called in your part of the world). Basically, from what I've read, if it poops and lives in fresh water you can use it. But if you don't intend to eat it I would think goldfish would be your best bet.

Check your local laws, but good candidates for edible species include...

Talapia are a very popular fish to grow in an aquaponics system because they cope with a wide range of water conditions, they eat everything and are apparently good to eat, they breed readily and grow quickly. If they are legal in your area, from what I've read they seem like the best choice as long as you have warm water. Talapia covert food into fish very efficiently.

Trout. If you are in a colder part of the globe you might try trout. Trout enjoy water that's less than 20 deg C. Its often possible to grow trout as a winter crop as they grow very quickly. Trout are often farmed commercially and are known for their conversion rate of feed to harvested fish fillets. ie It takes a relatively small amount of feed to grow a trout. I think that's because they do a lot of sitting still.

Carp are another pest species for Australians so are a no-go area for me. They are full of bones and taste like mud. Many Australians have a poor relationship with carp because we think they are full of bones and taste like mud. Australians also thought they tasted so good that they would import them from Europe and release them into waterways, causing insane damage to eco-systems that were poised on a knife-edge of sustainability just by virtue of being in Australia. Full of bones, mud.


Yabby. The yabby is delicious. As are marron. I'll be trying to grow some yabbies and/or some marron.
They breed in captivity, eat scraps of food left by other fish, and generally clean up your fish tank. I am trying to work out a way to keep them separate but living in the same fish tank.

[more in this post on marron]

Silver perch. Silver Perch seem to be the most suitable species for me to grow based on my location. They are good to eat but are a little slow to grow. They have high levels of omega three fatty acids, whilst retaining a clean white flesh. They are omnivores, and will eat things like lettuce and duckweed (a very small, floating plant I'll try to grow in nutrient rich barrels of water for fish food) From what I can gather they can take a wide range of water temperatures but might not grow much over winter. They also tolerate a wide range of water pH. If all goes well, I should have fish for the plate within 18 months, and then have a constant supply after that. Silver perch seem to get along with little silver perch without all the cannibalism that comes with some other species so I'm hoping to keep 3 or 4 different ages of silvers all in the same tank.

Not just Aquaponics - Fish, http://120thingsin20years.blogspot.com