Backyard Aquaponics
A place to discuss aquaponics

Given the space and extra tanks you would grade by size fish of the same species into separate units.
How big a difference in size is acceptable? How would you deal with this variation in size in a single tank?

If there are realy small ones in the school, you might want to separate them to intensive care and feed them well.

I have a the moment fish in the FT from 5cm to 15cm. A 10cm difference is enough to make the decision I guess.

Hi
I have been thinking about this all day. You are right. Thank you. Sometimes you just need someone to state the obvious.
I am lucky in that this FT is fed from above. What I intend to do is add an additional 80L tank above the main tank. This will be a simple flo thru.
I can then, separate and ‘fatten up’ the little ones.
I forgot to mention that the fish involved are Rainbow Trout.
What I have been doing is initially feeding with larger floating food to attract the big boys and then adding the smaller sinking pellets for the little ones.

Maybe that will work... generally I think "runts" are runts and no amount of extra feeding is going to make them into normal size fish. For a hobby system I suppose it doesn't matter, but I think commercial farmers (of all types of animals) cull out the runts because they're not efficient (they eat just as much but don't grow to the same size).

We just love the little fishies so much that can't just cull them.

Give them a chance Titus, May be they are just younger than the others and will grow eventually.

I have only two tanks for my RAS SYSTEM.. I divided them to large and small, and now, many of the small are approaching the size of the large.. I really could do with a third tank. To re-split the small again.
but.. I do see some rules, and I do wonder about them..

I also had over 100 Koi Cull in my death system.(now fully functional and rehabilitated) with a great many rules, many of whom were removed to an isolation tank.. and few of them have really done much.. good for a fish bowl..

So, the reality is that whilst we love them all, we are going to kill them anyway, and so the best thing is to do it earlier, ie. When they are clear runts ..
You could do it.by placing in a water container and placing in a freezer so they just shut down...
..

I have no experience of live stock rearing and of runts. So I stand to be corrected. Commercial fisheries will grade fish regularly using multiple tanks.
Economical use of food. This would seem to me to be a no brainer.
The problem in the backyard setting is that we don’t have the multiple tanks.
So as often we have to strike a compromise.
My use of two types of food, floating and sinking was my attempt to strike such a compromise.
Sometimes however you have just got to go with the flow.
Sadly the small tank I ordered arrived with a split so I cannot incorporate this weekend. Replacement next week. Don’t you just love E Bay!
I think we in the UK are spoilt. I can order by 7pm for next day FREE delivery.
A simple straight flo through with the small tank above the main.
Que Sera Sera!
PS listening to Susan Boyle. I dreamed a dream. Shivers!
Have a great Easter.

The tank arrived. Just a cheap 80L oblong box. A ‘T’ in the 22mm supply line with tap gave adjustable supply of water.
Simple vertical 40mm SLO down to the main tank. I did add a 40 to 22mm reducer as the water enters the main tank. The idea being this will increase the force of the flow and good for trout.
Moved the four smallest fish into the tank. Gave them a day to settle and then fed them. They were hesitant to hit the food. As if waiting their turn. I have seen this behavior before where at feeding time our dogs had an agreed pecking order. Anyway next day. Bang as normal trout feeding.
Too early to tell yet but I am encouraged.