Backyard Aquaponics
A place to discuss aquaponics

[quote="Chappo"]I know zilch about Trout but everything i know about fish in general tells me 1% must be a mistake.

It depends on water temperature and the size of the fish but all the tables I have seen recommend fairly similar feeding rates. These tables are set out to achieve the best possible FCR's, by feeding more you can increase growth somewhat but not so efficiently. In general feeding fish until they stop feeding is not going to achieve optimum growth rates and will be wasting food.
There are many Rainbow Trout feeding guides on the net, below is an example of what one feed company recommends. These figures are based on a water temperature of 16C, cooler water will require even less feed.

Fish size Feeding rate as % body weight per day
70 - 100gms 1.3%
100 - 200gms 1.1%
200 - 300gms 1.0%
300 - 500gms 0.9%
500 - 750gms 0.8%
750+ 0.6%

It should be remembered that the trout everyone are growing on now are 10 - 11 months old and dont require the high feeding body percentage rates (5 - 10%) that fry do.

*Phew* - I tried to double the feed tonight, and they were not interested at all. No food for trouties in the morning.

And I tried to weigh one today but no luck, little bugger flicked that much water out of the weighing vessel that it weighed the same as before he went in

Anyone got a length to weight approximation chart?

I guess it just shows have fantastic Tilapia are ,, eat heaps grow super fast and still get a good FCR.

Thanks troutman , I'm glad this topic came up BEFORE I got trout one BIG hsm would have occured.

Duh... of course... you idiot Rupert....

10-11 months old? ..... If Tilapia fingerlings are old but small they are considered trash ..... they have lost the growth spurt of youth ,, waste of time to feed them as they will eat little and grow little. Trout seem to have very different rules.

I'm having a problems with food input Vs growth .

Assume 1 Trout fingerling purchased at 70 grammes.

Assume a wonderful convertion ration of 1:1 , food to weight gain of fish.
Asssumer 30 days per month
Assume fish weighed and food levels adjusted once per month.

70 gramme fingerling ( well a friggen big fingerling) recieved february 1 .
fed at 1.3% body weight per day for the month( as per troutman recommendations)
MARCH 1 , 30 days at 1.3% is 39% still assuming a wonderfull 1:1 convertion , we have a , 98gramme fish
Ok close enough to 100 gramme... we now moove to 1,1% feed for 30 days ..... so a 33% gain for month
APRIL 1 we now have a 133 gramme fish .....,Feed rate sxtill suggested at 1.1%, so a 33% gain for the mointh
MAY 1 , we now have a 178 gramme fish,.....,feed rate still suggested at 1.1% , so a 33% gain for the month
JUNE 1 ,we now have a 237 gramme fish .....,,fed rate now is 1%, so gain 30% for month
JULY 1 we have a 309 gramme fish,,,,feed rate 0.9 % or 27% gain in 30 days
August 1, we have a 385 gramme fish,.....,,,feed rate 0.9% or 27% gain in 30 days

Figures not adding up for my planned 9 month system.
I guess i better over feed:) or is that NOT under-feed

Aaaah, but Chappo - when you overfeed Trout, yes they do get bigger, but there's no extra meat, they just go fat

The bottom fish was 820 gramm, the others were 5-600. The 820 gramm definately did not have an extra 200 gramm of meat, but did have a big belly full of fat.

That's interesting, I've noticed some of my trout are getting a bit of a belly on them. I might reduce the feed a little bit.

... because it's too cold for bacteria to live here? I don't get the joke?!

the MP's?

yep MP's ,, most people consider them bacteria.

Obese Trout , definately not the way to go.
1% it is

Hmm interesting, thanks trouty
Those numbers you were talking chappo, seem to work out about right.
Allowing for exponential growth...
So 1 kg by Xmas This I know

Chappo, different rules depending on the market. Farms growing trout for the table could have 500gm fish by now as they would have pushed them on over the summer. Fish to be on sold for dam stocking/aquaponics etc are held at high stocking densities in order to retard growth. By doing this more fish can be grown and they can be sold at a cheaper price per fish once the water temperatures have cooled down enough.

Thanks for your patience and info troutman.
I wonder if anyone has experimented with trout re age and growth.
I know with Tilapia a 3 month old 5cm fingerling will grow many many times faster than a 12 month old 5cm fingerling.

Anyway , different fish different rules.