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 Post subject: Re: Crayfish system
PostPosted: Apr 13th, '12, 04:50 
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yes this is not gonna keep me eating craw fish even weekly but it would be more efficeint. maybe clams or mussels are a better idea?


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 Post subject: Re: Crayfish system
PostPosted: Apr 19th, '12, 11:31 
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Hi all, my first post (will post in intros shortly).

I've had a bit of experience in aquaculture back in the day when yabbies were going to make everyone with a farm dam a millionaire. We kept a lot of yabbies (C.destructor) in intensive systems for research purposes. The good news is that it's quite possible to keep a self sustaining population of yabbies in a small intensive system at decent stocking densities if minimal husbandry requirements are met. This to me indicates that yabbies are a good candidate species for an aquaponics setup. *caveat* I have no experience in aquaponics whatsoever so there may be some other factors that I'm not aware of.

The key (as I see it) is to provide size appropriate habitat in a system for various life stages to avoid yabby on yabby (blue on blue ?) morts.

We used seedling tubes (150x50x50) siliconed together in a 5 long by 4 high (an honours student actually worked out that this was the best height :) ?? ) unit with the middle bottom tube filled with concrete to weigh it down. Quite a nice sight to see the feelers and claw tips of 20 yabbies poking out from the tower block. For the juveniles <20mm we wadded up onion bags and tied them into balls and did the same with loosely bunched shade cloth for the intermediate size classes. This has worked quite well for me since in a backyard tub grow out system although it works best if you size grade the yabbies once in a while into 2 or 3 inline juvenile tubs (with size appropriate habitat).

I'm looking forward to getting a yabbie aquaponics setup going when we move into our new house (not until August :cry: ) but have a lot more research to do!!?? Hopefully I can find all the answers here :D

btw I have a photo of the tower setup but don't seem to have posting permission as yet.


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 Post subject: Re: Crayfish system
PostPosted: Apr 28th, '12, 00:09 
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Sorry, forgot to post a pic of the yabby ghetto, hopefully this works...

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 Post subject: Re: Crayfish system
PostPosted: Apr 28th, '12, 00:11 
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That didn't work sorry, can someone please point me in the right direction?


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 Post subject: Re: Crayfish system
PostPosted: Apr 28th, '12, 00:23 
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Fridge Magnet wrote:
That didn't work sorry, can someone please point me in the right direction?


Hi and welcome,
I'm interested in increasing the density of yabbies in my AP sumps, this info is great. It sounds similar to the EDU system thats been mentioned here before.

There is also mention of yabbie balls....

To upload a pic
click the "post reply" button,
scroll down until you see "If you wish to attach one or more files enter the details below"

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 Post subject: Re: Crayfish system
PostPosted: Apr 28th, '12, 01:11 
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pic's have to be a max of 800x600 to place in a post
most image editors will let you do this with a couple clicks

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 Post subject: Re: Crayfish system
PostPosted: Apr 28th, '12, 10:38 
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yea EDU's have been around for a long time now

...and is cage farming in its greatest form.

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totally discusting..

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 Post subject: Re: Crayfish system
PostPosted: Apr 30th, '12, 11:54 
And it doesn't work.... doesn't produce the size or numbers claimed... and can't do...

A total failure....


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 Post subject: Re: Crayfish system
PostPosted: Apr 30th, '12, 11:57 
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spot on Rupe :thumbright:

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 Post subject: Re: Crayfish system
PostPosted: Jul 27th, '14, 12:53 
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I would think that EDU cells could be easily made out of plastic bottles. In order to be reusable, all that would be required would be for the neck to be wide enough to remove the fully grown crayfish (yes, Yank here). That said, I quite agree with those who say this is nothing more than cage/battery farming. Do crustaceans care? From observation, I believe so. They actually do have distinct personalities and behaviors. But....that's a matter of ethics, not aquaculture.

My reason for posting here: I have been experimenting for several months now with a small-scale aquaponics, using a 20 gallon aquarium for the "aqua" portion. Water is circulated on a 15 minute on/off cycle through two gravel beds which contain various plants--approximately three complete water changes per hour (running it constantly led to overflowing in the gravel beds). At this point I am using a wide variety of plants in the hope of discovering which will thrive best.

I set out to build a "self watering indoor garden", planning to trap minnows or similar to populate (and contribute nutrients to) the fish tank. My system is, obviously, not large enough to produce food fish. When my traps caught nothing but crayfish (and one small catfish, who has taken a few nips but remains alive and well), I decided to give them a try. I read a great deal about keeping crayfish in tanks. Most of which, based on my admittedly brief experience, has proven to be wrong. For example, in articles referring to keeping crayfish as pets, it is commonly stated that 20 gallons of water are needed for one crayfish. I currently have approximately 20 of varying sizes in a 20 gallon aquarium which is less than 75% filled with water. In addition to water circulation, I have a 40mm air stone running continuously.

While crays are clearly territorial and mine do fight on occasion, it appears to be "show" for the most part. When introduced, they varied in size from 1-10 cm (approximately). None of the adults at this writing shows any injury or signs of an attack, and the little ones all appear to have survived and have grown. I have seen small ones crawling over much larger adults and for the most part they appear to be ignored.

I placed discarded plastic pipe fittings and pieces of pipe on the bottom to serve as "burrows" (no gravel in case I ever need to "vacuum"). They have taken to them quite well and in some cases have rearranged them to suit their wants/needs. At this point I have no plans to add more crayfish (at least for the present). If I did, I would also add more "burrows".

The major difficulty I am having at this point is that I do not seem to have enough grow bed area (or enough plants) to "filter" the water properly. The gravel beds keep the water clear and I am doing fine on Ph level, though I plan to add some limestone to the system soon. However, the current plantings are not removing all of the crayfish waste, or at least not enough to reduce the smell (the room my system is in smells like a late summer swamp). I am adding plants and if necessary will add more grow beds. All of the plants thus far appear healthy and some are growing at least twice as fast as they have in my experience with "conventional" planting. It remains to be seen whether they will flower and fruit when that time comes.

Similarly, I do not yet know whether the crayfish will breed in such close quarters (of course, I can always catch more, at least until the streams freeze over). I do have a small tank I will use as a breeding tank should I notice a female carrying a "berry". Surely I will have to replenish my stock at some point, though thus far my mortality rate has been zero. Obviously I do not expect that to last indefinitely.

Feeding has been no problem. Thus far I have been giving them freezer-burned or spoiled meat every few days, along with vegetable waste and expired canned goods (corn and peas) discarded by a local food bank. I have duckweed growing in the tank as well and they seem to like that--will "porpoise" across the surface to collect it. As long as I see "food" on the bottom of the tank I do not feed them. Thus far there have been no problems due to apparent food shortage.

I am using Orconectes rusticus or "rusty crayfish", an invasive species which has done considerable damage to fisheries throughout the upper Midwestern United States (they are native to the southeastern part of the country). They are larger than the common crayfish native to this area and have in large part displaced them since they are more aggressive and destroy aquatic plants which serve as spawning beds. They will, by and large, eat anything. Characteristics which are dangerous in an invasive species but useful in captivity, so long as they are not aggressive toward each other which they do not appear to be.

I would be interested in hearing of the experiences of others in using crayfish basically as "fertilizer makers". Mine are currently supporting approximately 40 (for the moment mainly small) plants and could feed more based on the nutrient level in the water. Provided the population remains stable, I suspect I could add two more growth beds without difficulty.

I hope to hear from others who have had experience. And if anyone has managed to produce sufficient crayfish to generate a food crop, I would like to learn more about that. What is your tank size? What sort of population density? And how much surface area should be required for filtration/plant growth? I presently have more than twice as much surface area dedicated to filtration/plants as I do to the crayfish tank, and it does not appear to be enough.


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 Post subject: Re: Crayfish system
PostPosted: Jun 24th, '15, 13:06 
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What I am thinking is to build these submarines and burry them in the bottom of GBs to grow yabbies' in them. The ends are closed with caps and the feeding tube is secured.

Even in a bell siphon system, there will always be water in the bottom of the GBs.

Submarine is buried so it doesn't allocate growing space on top.

What do you think?


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 Post subject: Re: Crayfish system
PostPosted: Jun 24th, '15, 15:51 
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Might need to aerate but looks interesting.


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 Post subject: Re: Crayfish system
PostPosted: Sep 21st, '16, 10:15 
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That'd be a lot of little submarines or one very large one where you hope they don't kill each other. After reading through this I agree it is cage farming but my train of thought is what if it's just to get the babies up to a good size before releasing them into a DWC system with pvc hides? That way they are of decent size and less likely to be attacked by the others. And for feeding you could just attach some tubing to each unit and slide a few pellets in and if there's a problem with that getting clogged you could use a snake like they do for drains. Just some thoughts. I don't like battery farming as much as the next person but I think this could be the easiest way to maximize your "crop."
Another thing to note is here in the states they grow rice with crawfish then drain, harvest, and plant soybeans. Don't know if that's useful but I found it interesting.

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 Post subject: Re: Crayfish system
PostPosted: Jan 17th, '17, 05:59 
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I am thinking of adding crayfish to my system as tank cleaners. My perch don't like the floating pellets so I have to grind pellets in the blender and the smallest bits fall to the bottom. In a square 330 gallon tank, how many would I need, especially since they compete for space? I hope to find some big enough so the perch don't eat them. Any thoughts?


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 Post subject: Re: Crayfish system
PostPosted: Jan 20th, '17, 14:07 
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Depends on how big your perch are, but crayfish attack just about anything that moves. It's recommended that you give a cray about 5-10 gallons per so with that math about 33-66 give or take. Obviously that's gallon wise but they prefer the bottom and won't be swimming all that much so you'd probably be even lower than that and only be able to raise around 10-20 if you're lucky. They also like to hide food and will cannibalize each other or fish so im not sure just how "clean" your tank will be. They also need hides which will allow you to raise more in a confined space and protect them from each other. That being said, size wise, depending on your perch, I'd say around 4-6" minimum with some hides and see how things go from there. Best of luck.

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