Backyard Aquaponics
A place to discuss aquaponics

good info stu.

I'm fairly sure trought have a higher fat and lower protien requirement. Check up some ridley specs on their website to confirm

Hi,

What is the benefit of using larvae to raise feeder fish......given that the BSF larvae start off as live food anyway?

On the matter of fat content, if BSF larvae are an issue because of their high fat content, why not just feed less of them?

At the end of the day, we should be seeking a balanced diet. For me, that means some larvae, some duckweed and some......(I'm still working on the last bit). In the meantime, it's fish pellets.

Gary

I'm thinking BSF would be good food for crustaceans like yabbies, marrons, redclaw, crayfish or shrimp -- because of their high calcium content. Would the crusties stoop too eat "larval protein?"

3 days in the poo and no noticable poo mass reduction. Which means absolutly nothing because I'm only using 800 BSF to a gallon of crap.
I have no desire to feed my fish only BSF. They will, hopefully, just be an addition to their diet.

Thanks for the digging Stuart. I wonder if there would be more or less fat in the BSF larvae fed mostly on vegetable scraps opposed to manure?

On a smaller scale, BSF may only make up a small part of fish feed. But think about in a situation of farming fish, 10% of the feed is still a significant amount, and will cut costs quite reasonably, Once again, press out the fat! (Musing....anyone know much about cost effective small scale oil presses? )

GotFish, you make it sound so elegant:

"Only 800 BSF to a gallon of crap."....Simply beautiful.

Hayden

All I wanted to do when I started APing was grow fish and veggies, now I'm raising worms and attempting maggotry. When does it end?

Just as well you're not raising sheep

You would need sharks in the tanks to eat the sheep. Mmm flake.

Nova

Remembered a query on what a slater is when I saw this:
there are slaters......and their are slater predators

how cute is this little guy?

http://www.wiz66.net.au/index.cfm?sid=9 ... item=20642

GD


Absolutely. However since they are really easy to culture I'd like to feed as much of them to my fish as possible. That might not be that much though (>30%?).



I agree but the trick is that last "bit". Theoretically the smaller the last bit the easier it will be to find something to fill it. Weeks ago now I think I remember something about recommended feeding rate of earth worm meal to fish was around 40%. Combined with BSF that still leaves a fairly large bit to fill.

VB has suggested that I make my own pellets using egg, sprouted grain and whole meal flour to fill the bit. May work but from what I'm reading may not be the best choice.

Check out

http://fishnutrition.uoguelph.ca/feedint.html

Section 6 states that that fish (salmonids in this case) are not very good at utilizing vegetative source of food. Table 6 suggests that salomnids can extract plant derived protein (around 90% efficiency (which means that the high protein, low carb content of sprouted grain could make it a good choice)) but the total energy (balance of food being sugars starches, etc. (suggesting that flour might be a poor choice)) is underutlizilsed. Obviously this would have to be different for SP and Tilapia but for those with predatory fish might be an issue.

I've asked this question before so if it got answered I'm sorry but I missed it.

In ACulture systems these questions are really important because any food that is not utilised is not just waste but pollution that is expensive remove from recirculating systems. In AP do we care (or should I say is it important)? Lennard Wilson would care with his system design require solid filtration and removal but if any wastes just goes to the gravel grow beds do we?

If we did then a poly culture with yabbies could be an easier solution rather than trying to get a balanced diet. Any thing that the fish don't eat, digest or metabolize gets sucked into the yabby tank. No head aches, stress or deep thinking. I'd prefer that if it it would work.



The idea is that if you can find a feeder fish, crustacea or something that can metabolise the fat and convert it into useful fish food (protein or ?) then you could take a high fat food and produce a moderate to low fat food.

Deep breath,

Stuart.

PS went to Colac yesterday for my Grandmothers funeral . Afterwards I went to what is now my uncle and cousins farm (Gellibrand) in their worm farm I found BSF .

PPS Just found some of the answers to my question on trout diets. Crude protein must be great than 46% and fat greater than 23%. Unless you are feeding them the Norwegian doughnut diet of >36% fat.

So is the answer ... feed them anything they will eat but in moderation?

Sorry about your loss Stuart...

I guess what your suggesting is going to work to an extent, but then by feeding the poor diet to the fish aren't you adversely affecting the health of the fish still? It's not just about dealing with what doesn't get metabolized..

For some reason I have an image in my head of an analogy with a rather obese child in a tank being fed piles of junk food, dropping bits of junk food everywhere, and excreeting lots... Someone comes along and says "throw some rats in there with him, that will help clean up the muck.." Sorry, not really a pretty image...

I don't think waste food is as much of a problem in a gravel bed AP system that pumps the solids into the growbeds, as it is for other systems like aquaculture, or AP that requires filtered water. Though I think it will work out easier to restrict the food to a near balanced diet. As your biggest input into a system is the food, ultimately your making more work and expense for yourself by inputting more than what you need..

Thanks EB but she was 91 so thats a pretty good innings.



My fish nutrition is pretty sketchy (non existent two months ago) but I'm getting the impression that many predatory fish species use a significant (not most or half just a significant bit) portion of the protein in their diet for energy and are not particularly well designed for dealing with larger amounts of fat (except for salmonids which seem to be able to have over 36% fat according to some people).

The trick, if you wanted to go down that path, is finding something that masses of fat is a good diet for. The article I quoted in an earlier post suggested that wouldn't be Red Drum (american fish of comercial importance(?)) since the Red Drum fingerlings didn't metabolize the fat they stored it. That would be exactly like feeding the fat kid junk food and then feeding him to the fish, or the rats

I think a better idea would be a feeder fish that was either a vegetarian or omnivore. Yabbies could fit that bill and fill this missing bit in our BSF, earth worm diet.

I've still got to look a bit further into species specific diets amongst the salmonids but it looks like I can use BSf as a major part of my trouts diet without any worries. However I also want to take a crack at blackfish so still an open topic for me.

Stuart

Stuart, I am getting a lot of good out of your research and analysis. Thanks.

Because I am just starting to raise fish, I will probably establish some experience with normal pellet feed for a while before I replace much more than 10% with anything else.

I see what earthbound is saying about a fatty diet being like junk food.

I was thinking that feeding BSF to some organism (feeder fish?) might yield protein for my crop fish. I do not know if that would work. I would think feeding to crustaceans might work well, as ems suggests.