Backyard Aquaponics
A place to discuss aquaponics

I'll bet 90% of lobsters in this country are exposed to amquel while in holding tanks...not FDA approved. It gets scary!

The grading net" idea is a good one Ryan. How do you attach them to the tanks? Mine are poly. It would serve a double purpose to prevent the talapia from breeding if the lower one was off the floor as well.

Grading netting in my opinion could be result in fish injury (scale abrasion, fish entanglement) and become a breading ground for filamentous algae and parasites to attach, also in my case it would interfere with the system flow dynamics, preventing the cup flow effect created by the aerated bottom drain and stopping sediment accumulated on the bottom to free-flow towards the bottom drain exit.
I use a SEINE net to ghater the fish in one spot and then it's as easy as dipping a landing net to scoop out 5 to 10 kg in various size, then leave in the purging tank for 3 day and use small ones(400g) for pate' and big ones (500g) filleted and marinated ready for the smoker.
I have 1 and a half month to fully harvest one tank (350 trout) before it's time to move to the next one (staggered trout restocking/harvesting system) the fingerling are kept in a quarantine holding tank until it's time to transfer in the grow out tanks and let them go for another 4 and half month.
Each tank will have an average trout size 400-550g after six month grow out time started from 5" fingerling.
We keep biomass density at a max of 20kg x1000lt.

Charlie:
Aquaculture deal with many tonnes of fish and big harvest has to be done quickly due to the high perish ability of fish once dead.

as for stress on fish draining tanks?
try to picture yourself closed in a freight container with another 50 fellow friends...an airtight seal on the door....... and air is getting slowly sucked out of it...... do you think is there any stress there?

Troutman uses the draining method.