Backyard Aquaponics
A place to discuss aquaponics

perhaps have a tank that has these different sized grills, but also a movable fine screen to stop all travel.
Put all fish down the 'big end'
feed at the 'little end'
After a moment close the door
feed at the not so little end - close the door.
repeat until all doors are closed.
Then... after a few weeks of feeding. open the door between smallest and not so small.
hmm this wont work... they'll go the wrong way...
I need to think... perhaps the sized screens need to be moved...
hmmmmmm... this is going to irritate me now :-) come back to you tomorrow

TT - pumpkins will not generally rippen off the bush, not unless they are already ripe - in which case over a long period they will rippen further (until they are rotten ).

Just as well you got distracted TT..... been some people arrested for that sort of thing

Cues George Michael`s careless whispers

Hi TT,
If where you I would paint it white specially if t is for fry, because you wouldn't see a thing in a black tank. Specialy with larval culture that you will be doing with silver perch.

For the autograding fridge, I'm not to sure that it works if you don't pressure the fish through the grids.

Two solutions are done in fish farming, one was invented in australia with an air balloon bottom of main tank filling up and pushing the fish to different channels with different grids, all the channels are connected to the main tank and lead to different tanks the same size as the first one. It is a technique used to grade barra weakly.
The second is done in Hungary at the oulet of dams, they have a concrete channel that is attached to the dam outlet canal. The water goes through a grid that stops the fish and pushes them to the bottom end of the concrete channel fed the other end with fresh water with few different grids placed on the channel. It is then the fast flowing and fresh water that attracts the fish coming out of the dam and the grids grade the bigger fish on the bottom part and the top end is the small fish. It is a sort of loop along the dam that makes the fish go upstream.
If this is not clear enough as I'm not too good at explaining things like this, tell me and I'll do a drawing.

Another point very important for the larval rearing is to concentrate the babies so that they get access to high density of prey, the best is to have a bucket with an overflow that would be screened and would take the grease surface out aswell. You have to have a type of surface skimmer in a larval tank so that the fry can take a proper air bubble to create their air bladder.

For me the best solution is to do cages with a fine net, that could then be pulled up to concentrate the fingerlings for hand grading. Water would be fed from an exhauster air pipe, like an under gravel filter and pushing the fresh and oxygenated water on the top then pushes all the fish poo down on the bottom of the tank where it is pumped in the growbeds.

Hope this helps you, don't hesitate if you want more infos on silver perch hatchery techniques as I have done it at Ausyfish.

Thanks for the tips one and all. I will re read ur advice Amacafish. I would certainly prefer to use a white paint or sealer. Just not sure if it is available in a fish safe form. Anyone got any brands for me?
Believe it or not, this freezer is in Colac, same place I got the stainless milkvat from. Think I will just shift there and save on transport!
VB, I am really hoping I haven't jumped the gun on those pumpkins.

What type of eggs to silver perch lay? If you answer fish eggs your going to get such a pinch!

round translucent ones? :-)

I should of included that in a list of answers that would get a pinch.
Seriously do they lay them in a long strand like yellow perch or a gob of eggs on the bottom of a stream?

Can't remember the precise term GF, but they are a semi buoyant egg. It stems from their time as a sea species b4 they became landlocked. The buoyancy allowed for tidal dispersal to better increase the species survival chance. (Pelagic might be the word. ) More buoyant at higher salinities.

In recirc we need to provide gentle air from underneath to maintain these eggs in a semi buoyant position, (ie in the water column, not necessarily at the top of the water column.) Silver perch eggs would otherwise sink bc salinities in recirc are obviously much lower than a marine environment.

Murray Cod on the other hand, look for a hidey hole and substrate to lay their eggs on. They evolved from fresh water.

Why do you ask?

Thanks, was just curious. I am looking forward to your breeding and was hoping they were the same so I could get a better feel for what I will have to do.

Gotcha.Just read that article Janet linked to earlier in ur thread. Like silvers, yellow perch are oviparous, for others, unfertilized eggs are laid in the water and fertilized immediately by the male.

In the wild many many eggs are released in this manner bc of the relatively low survival rate. In recirc we can get very high survival rates from these highly fecund species.

GF, my plan is to spawn in the milkvat and net the broodies back into the large tank. The eggs are only a couple of mm in diameter so if my net holes are bigger, (they are) i won't net too many eggs when catching the broodies.

Then gentle air to keep the eggs in the water column, cysts and paste when they hatch and HSM when i need more than 6-7000 lts of water to keep them all alive!

It is by no means a foregone conclusion, but I am hoping to spawn them this season.

few pics, brassic seedlings and new lettuce are at 2 weeks

more

picked the first tomato today.Most of the 80 or so flowers at the top of the bushes have set, about 40-50 fruit at the base ready over the next 2-3 weeks. Should be a reasonably spread crop.Finished up with 7.5kg of little butternut pumpkins from 3 vines, now gone.The single eggplant has 6 more days to live, ditto the zuchs. Picking the second crop of lettuce and endive.
With a suitable fishload, I reckon around 1000-1500lts of gb space per person per family would cover the vast proportion of a families veg needs. If I can get another 8 gbs in, will have 4000lts all up. Should cover most of our non root crop veg needs. See how we go.

Broodies are enjoying being in the big tank, could easily have a couple dozen of them in there.