Backyard Aquaponics
A place to discuss aquaponics

Without doubt we are all prone to throwing in the odd bug found in the garden.

With any feed given to fish however in larger quantities that is going to be a main or supplemental food source, in general it is good to follow some basic guidelines:

a - will the feed harm the fish?

b - does the feed provide the fish with the appropriate nutrients for healthy growth?

c - do the fish when ready for harvest provide a healthy balance of Omega 3's and other nutrients for our consumption as compared with wild fish?

If we cannot satisfactorily answer the three questions above, any supplemental feed source becomes questionable, could be harmful, or provides a less than optimal feed vs. growth vs. output ratio.

Slaters for example, have chitinous exoskeletons (tough outer shell) which is composed of fibrous polysaccharides (chitin and cellulose). Therefore, (and I am just surmising a hypothetical) that a feed of slaters may not provide much nutritional value if the particular fish species cannot digest the chitin to sugar for example. Fish that eat plants would possibly be able to (, but those that are mainly carnivores may not.

Therefore, before throwing any food source into our tanks, (BSF included) it is important to know exactly what the nutritional value is of that food source, if the fish species can actually digest it properly, and if it is actually providing any benefit to our end product.

Gimme a little time Tony - I've got a few papers here (as .pdf's) looking at BSF nutritional profile, as well as duckweed, water hyacinth and a few others I think.

While I'm here - you've put some great work into this Tony - thanks and keep it up - we're all learning from you.

They're great points Tony. From the research I did earlier in the year, there's no single, naturally occuring food that has the perfect nutritional profile, so a mix is required, and this is exactly what you see in nature.

When you then throw in the differing nutritional requirements for different species of fish, and even different age groups within the species, you very quickly have a complex array of variables to try and match up.

Here's a couple of links... I've got a good one somewhere that I'll find later...

http://www.p2pays.org/ref/13/12648.htm

http://www.cals.ncsu.edu/waste_mgt/smit ... les/A2.pdf

This one might need some qualification...

http://www.nutrigrub.com/fileadmin/user ... is_PDF.pdf

Cool - found 'em.

Tony - PM me your email and I'll send 'em to you.

Hey Rup..
The report by Mike Williams is brilliant. Sheppard et al seem to have done the most work on BSF nutrient values and nearly all the papers refer back to those.

But ohhh to have such a collection system..!! Some serious dollars has gone into it.

Interestingly it does matter what the BSF are fed on i.e. the difference b/w vitamin levels and some essential amino acids varies quite significantly when they are raised on chicken manure vs. cow manure vs. organic scraps.

The report also goes on to discuss the value of BSF as a replacement for fish meal in the US Catfish farming industry but also the potential for the trout, salmon, tilapia and shrimp farms.

I note though it also talks about the high chitin content of the BSF and the digestibility of some species where it could become problematic. But so far it is all positive.

But leave it with me for awhile and I will come up with a rounded comparison analysis of each feed and see what it shows.

A lot of the US Catfish industry has gone away from BSF as a major component of feed...

Those that remain, render the BSF to reduce fat levels....

Yep that's interesting to know. I read the report mentioned the high fat levels. Obviously put too much on in the end I gather?

And thanks Chilli. Got that info. That was fast.!

I can feel an AP study coming on...

Yeah, true. I wonder though if that level of fat is better for trout and salmon which generally have higher fat feeds.

Reading some of the material out of northern europe regarding redfin, they find that the perches don't metabolise that fat very well at all and in fact it gets deposited in the liver and abdominal cavity, resulting in premature death. They get much better results with a high carbo feed, as that does get metabolised, still allowing the protein to be used for growth.

Remember also... that protein conversion from a feed source is always limited to the "limiting" amino acid....

Without getting too complicated.... another amino acids, even if they match or exceed the daily requirements for the fish... wont be capable of being utilised beyond the limit of the lowest amino acid provided...

Yep - gotta have the whole profile.

You've been paying attention during your course CD....

oddly enough - picked that one up from a friend that was into bodybuilding

Any chance we could see how your fish react to the HFLM feeding? Video would be awesome.

On the chitin content of feeds. In the wild a great percentage of natural fish food would have a high chitin content. Whenever ive caught trout their bellies are full of insects with the occaisional yabby. Redfin on the other hand seem to consume more fish and yabbies.