Backyard Aquaponics
A place to discuss aquaponics

poor muzz, i wonder if his fish will rebel onday, him waking in the middle of the night to see 6 perch in a trench coat poised with an axe........ LOL Sleep deprivation..........

hello everyone, juts a few thoughts....

we did some work on some systems in thailand (outside) and england (in heated barns) using AST acivated suspension technology to culture tilapia, AST bascially gets rid of the need for a recirculation system (water run through biofilters) by using bacterial floc (floculated colonies of bacteria) so these systems where basically 2.5m3 tanks of aerated water/bacteria soup with a carbohydrate source added for the bacteria to bascially convert to crude protein for fish food and maintanence of water quality parameters and some suplementary pelleted feeding. A closed low input system. but we ran into problems of controlling and removing the floc and dealing with stablising the bacteria communities, so how about the possibility of using floc as a aquaponic resource for the plant production input.? could work to remove excess nitrogen and be used in conjunction with settlement tank (plug/baffled-flow) to also provide a dryable raw material for inclusion into crude pelleed feeds.

and perhaps more interesting...

the direction that the trial took us and is taking us, may also be of interest in terms of fish feeding and growth. we are now trialling the impact of more natural feeding, for example a fish in the wild (that grows relatively consitently) will very rarely have a uniform diet as they do when cultured, instead the protein intake will vary depending on its respective inclusion in the prey item and the frequency with which they eat each prey item, so why not reflect this in the method of feeding we provide cultured/aquaponics fish. what i am getting at is that we are looking at feeding high protein (therefore often higher value) feeds at intervals, say one in 4 days, and then the other three days are made up of lower cost, lower nutritional quality foods, and the initial results from food conversion ratios (FCRs) across the trial and the controls looks very promising when doing cost benefits with consistently feed fish on high protein diets.

so something all you budding experimentalists may want to having a play with, my uncertainties lie in how this pulsed nutrient input and therefore outputs would effect the nutrients available for plant growth, do you think it may even be beneficial??

also have a look at a thread on how to remediate waste inputs from a aquaculture farm by integrating aquaponics into the bigger picture, still conceptual but all advice comments welcome.

cheers
charlie

I just did a quick calc. Barra are reputed to grow to size in 6 months right? So if you assume a FCR of 1.5 to 1 to be pessimistic/conservative, that would mean that it would take approx 150 kg's of food to get my 200 fish up to 500 grams each, that is a total of 100kg's. Now to feed them 150kg's over a 6 month period would require an average feed of over 800 grams per day. Have I lost the plot?

If you use the following data, you will have 500g fish in about 200 days using 71kg of feed.

Fingerling Size 35g
Feed per day as % of biomas 2%
FCR 1.5
I have the (basic) spread sheet if anyone is interested

Thanks, would love that if possible. Was wondering about how much % to feed each day. I could easily weigh 10 fish to get an average.

if you have it available, put it on as a download

Added to dowload area as feed and growth.zip

cheers

brilliant royale, been looking for somethinglike that for ages. Might try and bring a bit of science into my feeding LOL.

Excuse the spelling errors- defining bioass may give some trouble

LOL... beggars can't be choosers....spelling errors are common place around here, but bioass is one off the better ones!

VB do you make your own pellets?????????

My Jade Perch (44 in number) are about 18 weeks old and live in a 700 litre tank.

I feed them about 80ml of small fish pellets most mornings and nights. Every now and then, I get seduced by the sight of fish slapping the water and jumping around, and I feed them more.......which usually results in a nitrite spike and no more feed for a couple of days.

We feed as much duckweed as we can produce. Our duckweed tank has quietened down the past few days as the temperature has been cooler than usual.



.....and are very illegal in Queensland where you are liable for a fine of up to $150,000 for keeping or distribution.

Sorry CG - have only just seen this post. Answer is no - not at the moment but I think it is something that I will definitelly give a go if I ever find the time.

Garry - I know I don't need to tell you this, but for the sake of newbies reading this thread, more plants would mean that the nitrite spike would be avoided and you could feed the fish what they wanted. I'm quite sure from my own experience that perch (jade and silver) do not guts themselves like I have hear Barra can do. I feed them until they stop rising for the food.

One of the stories that I like most about Jade Perch is that, according to a DPI officer, a fish farmer in Central Queensland is feeding his Jade Perch up to 70% duckweed.