Backyard Aquaponics
A place to discuss aquaponics

Also I am of the understanding that slaters are related to shrimp and prawns, so may not be a bad source of feed for fish, I also may be wrong but this is what I have been told

Not sure what it is about peoples fascination with slaters, but as has already been mentioned earlier, they and just about any other garden bugs and insects (crickets, worms, cockroaches, caterpillars, millipedes, etc, etc) could be used, theoretically. But I don't know how to farm slaters, nor do I know if they have any nutritional value as a replacement feed. It would be great for someone to research the whole story, and start up their own thread with the results and would make a highly valuable project for AP if the data stacks up (for a particular species of fish that can digest them). The point of any replacement feed is just like Rupert stated "the protein conversion from a feed source is always limited to the "limiting" amino acid...." Hence, if you throw it in your tank regularly, know what it consists of. Just because the fish eats it, doesn't mean its any good for them.. Look at humans and deep fried / fast food..!

Couldn't agree more Stuart. Any fish that eats insects and crustaceans will be able to digest Chitin. Interestingly, chitin in crustacean's (yabbies, prawns, crabs, etc) is a natural biopolymer from which glucosamine and N- acetyl-glucosamine can be produced for human consumption. Many derivatives obtained from chitin also have a variety of biological properties including anti-tumour, anti-infective and antimicrobial actions for humans.

And to recap Chilli's well structured wording:
Hence, why I am putting forward HFLM as a potential high quality substitute / addition to any fish species regular food supply as it does not matter if the fish is a natural herbivore, carnivore, insectivore or any combination thereof. Additionally, like BSF, the nutritional profiles have been well researched for aquaculture purposes and therefore both BSF and HFLM are highly suited to nearly all AP set ups. And HFLM production is free, easy, can occur all year round in ALL states, and you can make truck loads of them to freeze for a rainy day.

No worries Bob. Leave it with me. Not sure how to upload video's. Never bothered with YouTube, but why not.. Everyone else does

If you don't have a strong stomach, I'd look away now from the next lot of photo's.

Unfortunately every day driving to work, there is at least 1 possum that becomes a victim of the motor vehicle. So, for us there is a steady supply of carcasses to put in the Biopod. But any meat scraps can be used (but not fat).

And after 2 weeks, there is very little left but skin and fur.

HFLM can be seen busy within the fur eating what little is left. A number of maggots have pupated and not made it out of the Biopod. These can also be thrown into the tank once harvested if you so wish to take the time.

Once the carcasses are around 90% composted, I tend to throw the whole lot into the rubbish bin (on collection night ) and clean the Biopod out ready for the next lot. But as mentioned, it then takes an additional 7 days or so before maggot production will resume, so having some in the freezer can be a handy thing.

Wow, brilliant work Tony.. So any idea roughly what sort of conversion your getting? For a 4kg possum what weight of fish feed did you end up with?

poor possum . . i know when i lived in tas the amount of roadkil was astounding. but then again that indicates a large population of animals . . . . .

I also noticed the large amount of road kill in Tassie. . . and the (legislated) distinct lack of Foxes, which would normally clean it up on the Mainland. Ravens and Crows can only do so much.
Cheers IanK

And I guess Tassie devils are having a hard time of it recently with many being wiped out..

We have legislation and an intense amount of work to keep foxes out of TAS for a very good reason - It would absolutely decimate every facet of our entire wildlife population.!!!!! Now that is an excellent question.! I am about to clean out the bucket this weekend as its starting to smell a bit anaerobic and the carcasses are all but done.

I think the most important question though is not the total weight of the total HFLM but rather how much energy is produced from the HFLM as compared with fish meal (and BSF) gram for gram when eaten by the fish. There is plenty of info on how much fish product it takes to make 1kg of meal, but not sure how many kilos of organic material it takes to produce 1kg of BSF.?

So I will weigh the next possum (which is currently laying in the back of my ute tray ) before putting it in the bucket and then start weighing the end product. From that I can easily work out the energy / protein output and compare the 3 feeds from existing available data. You have me intrigued..

Rupe, if you could throw your opinion here too, that'd be cool.

Tony, I don't think you'll get impressive figures if you're comparing them to pellet food as you're comparing wet food (your stuff) to dry food (the pellets) - i.e. the contained water will dilute your figures.

Many marine fish hatcheries maintain their broodstock on wet food (squid, mulies, flesh, etc) because that's all they'll eat - and the FCR is corresponding lower on a weight basis.

Tony, great job! Love the pics. Even if the maggots aren't providing an overwhelming amount of nutrition for your fish, your still providing a great service for your community. Not only do people have to deal with less roadkill (sights, smells, continuing to run over it.)

As stated, it is very likely that these maggots DO in fact provide nutritional value, although the amount and effectiveness is being debated. With that, you're also helping out your wallet by providing supplemental feed to your fish. Bravo!

If a more accurate picture of the nutritional content could be developed it would be interesting to see how it compared to whatever feed you bought, then break it down into how much money each maggot costs and see how long it would take for the BioPod to pay for itself.

I myself am a hunter, and of course after quartering a deer you are still left with a lot of scrap (not to mention the gut pile) that could easily be used in something like this. I only live about 3 miles from where I live, so occasionally I see roakill, but it's not often. I do live in the country, though, so if that is in short supply I could always set some mouse traps outside and see what happens. I'm just thinking outloud now, but there are a great number of possibilities for this type of setup.

Hi Tony,
When you say house fly do you mean the little black flies that stick to you or are you talking about the bigger blow flies?? Also what components do you need to make one of these biopod thingees, I have a house composter that lost its charm very quickly but doubt it would hold a possum without me disecting it, and I don't want to do that

Cheers Carol

I'm not sure I agree here Chilli. Wet food is nothing more than dry food that has been 'dried'.

It is dried so a nutritional content can be analysed. On the whole however, the same nutritional content remains in wet vs. dry and it is relatively easy to extrapolate the data b/w wet weights and dry. e.g. we know how much wet product it takes to make 1kg of dry weight for instance.

Realistically though, HFLM is more suitable as a really nice 'supplement' feed unless you are able to set up quite a large production system. And I can tell you, that would require access to huge amounts of carcasses as the HFLM make VERY short work of anything thrown in the bucket. For example, Yesterday I popped in a possum and thought "I'll clean out the remainder tomorrow." 24 hours later it had already been degraded to the point I didn't want to pick it up again..!

NY State and Canada have massive problems with deer carcass disposal. Such massive composting sites would provide ample opportunity for a commercial feed source. Deer and Moose aren't in huge supply in Oz though, but Kangaroo's are..!

Also, it could be easily debated that wet food will always provide much better 'natural' food sources than dry food ever will. There is much more to eating wet food than just protein and lipid profiles. Any animal (incl humans) are much more prone to disease and immune related issues when fed solely on processed dry food.

House flies are always the smaller pesky ones. Blowies are much slower and far easier to slap..!

You will always get both fly types in the collection bucket. The blow fly maggots are actually MUCH fatter and juicier, and weigh more obviously. The profiles are the same. I have noticed over the cooler months there were many more blow flies. With the warmer weather, house flies have taken over. Either way, production still continues at a high rate.

Additionally, many maggots will make it to the pupae stage and these can also be thrown into the tank. The fish love these too. And they have the benefit of being semi-sinking so will hover in the water b/w various depths.

Thanks heaps Tony, I have started to make a larvea collection station (don't want to call them maggots) so cut the top almost off a 25lt drum, just so it will hinge on itself, and made the walkway out of some white conjute that I had laying around, think it might be 3/4 inch white stuff though not the usual orange, so have all the bits ready to put together with silicon when hubby had a fit and had to abandon the whole idea, he will forget about it so will get it finished later have put it in my "girls shed" so he does not have to be reminded about it. Thinks it is going to attract flys....well yes I hope so... and thinks it might smell, well time will tell, thanks so much for your great advice and trials on this subject and anything that helps feed the trout for free must be worth a try. Do I need to put a tap in for a drain plug and is it best to be kept in the shade, still need to drill some holes in it for entry points for the flys yet but that will take no time at all.