Backyard Aquaponics
A place to discuss aquaponics

I was just transferring some barra from the vat to the poly tank, and trying to grade the big ones out, but I got a bit scared they were going to cark it on me. Does anyone know how long the fish can survive out of water, and how much handling they can tolerate. When I dropped them in the new tank, they didn't look that great, and now they are very still on the bottom

I just rang the hatchery where I got them from. I should have done that before moving them
He said to get a plastic tray with enough water in it that keeps them on their side, butand stops them flapping, and then grade them out either with a small net or by hand as quickly as possible. They do it using machines, which makes it quick and easy and minimal handling, but he said the grading process was the biggest weak point of the whole system.
Anyway, he said as long as their gills stay wet, they should be okay. Mine are now ramming their gills, he said that is due to both stress and having their gills out of water for too long
I'll be spewing if I have killed them, only time will tell I suppose.

grading is a s**tty job. The way I had to do it was hell on your back and arms. The fish were out of the water for a minute or two (fingerlings up to 7cm)

well if they are anything like Silver Perch, they will be fine. Sounds like you did the grade fairly well.

At tafe, i thought i was being Kind to the fish by cradeling them, rather than holding them, well they jumped out and splat on the ground. It survived though!!

GRADING TIP:
when grading if you are handeling them keep your hands moist, it benefits you and the fish, as the protective skin mucous stays on the fish where it is needed and off of your hands


Did you weigh or measure any? or just move them?

Just moved them. I panicked , they were only out of the water for maybe a minute, while I counted them. 27 in the polytank so far.

i know that with both jade and silver perch if you handle them at the lower end of their "happy temp" say 14C for jades, then the risk of problems is much greater. I assume it the same for any fish, so don't grade the barra if you're "just" maintaining a happy temp

Steve

and trout die after 2 minutes.According to the trout man he has seen fishos catch a trout take some photos and after a few minutes put the fish back without 'swimming' them, only for them to swim off and soon turn belly up!

I know i'm mean to be in bed, but i had one last look at the forum whats "swimming them"?

Moving water through their gills (usually hold gently by open mouth and wave fish gently into current) before releasing them

Why does that make such a difference to their survival? isn't water going to get to their gills as soon as they hit the water?

Not disputing it, just interested in the theory.

Theory is it forces greater amount of oxegenated water of gills ... refresheds them and brings them back to strength

Without it they can lie "gasping" on the surface trying to reoxegenate.

Don't/can't swim properly... don't/can't breath properly

This also upsets all there balance systems and generally stresses them to the point of death.. has been suggested that stress also leads to toxic discharge/build within fish organs like liver

cool, makes sense..........

I wonder if the trouts dependance on high DO and the fact that they like running water are linked.................

Thanks for the catch and release 101

to clarify ... fish breath by passing water over gills and extracting oxygen directly into blood flow in gills ... hence bright red colour of gills

Takes the place of our lungs

Absolutely 100% correct ... go to the top of the class

By the way ...

If you open the mouth of a fish you'll see that it also opens up the gills ...
hence increasing the surface area of the gills to water ... to oxygen uptake...

Ever seen fish "gulping" in sync to gills pulsing... swimming into current