Backyard Aquaponics
A place to discuss aquaponics

Went to a farm at Toolibin (60k's east of here) had 50 trout on wednesday and has lost over 20 now, 4 died when I was there, when he phoned me he said ammonia and nitrite were fine but got him to change 30% water anyhow as he has heaps of rainwater, got to farm yesterday and tests were pH 7.4 Amm .25 Nitrite 0, changed more water and turned system pump on and after about an hour fish looked happier and actually took some feed half jumping out of water, suggested more air, he did this and pkoned this morning another 15 dead.
Fish actually look fine other than being a little lethargic, no spots and gill area looks fine, fish around 200gms were got from Dumbelyung farm where mine came from, only a couple of fish at the surface but not gasping for air
This is the forth lot of fish he has lost in 18 months, this time he had black carp with trout but has had trout by themselves last time, water comes from a 50,000 lt fiberglass tank which is filled with scheme water in the summer and rain water this time of year, no scheme water has been put in tank for 3 months.
My assumption now would be, spray drift from neighbors farms settling on his roof and washing into main tank, would this be enough chemical to kill the trout with water coming from a big supply? farms spray weedicides and pesticides plus fungal controllers, I have obviously suggest he gets water tested as this his main drinking supply as well

i had a similar thing hapen to me with silvers, i was using rain water simply because i thought it was the best thing to use! turns out it isnt! I dont know all the ins and outs but pure rain water is aparently hard on fish, in regard to the fish i had as i was loosing them i split them up into 3 different system, 2 off them with nothing but rain water and 1 with scheme water, well the only ones to survive were the ones in the scheme water system, i have learnt to treat rain water with minerals, best thing i would sugest is zeolite, trout survivr well in our south west dams and streems and they have a reasonably high PH and i believe lots of minerals.

good luck to your friend.

I haven't had a problem with rainwater before Grunta, but their tank would be about 40,000lts of scheme and 10,000lts of fresh rainwater, more concerned for the people ATM but hopefully test will sort that out, he has a corry tank but also my corry tank that has been sealed, fish lived in my tank for over a year

Rain water is soft. Increasing kh and gh is often necessary. ie. Add sea salt and shell grit.

Nocky, what are the growbeds made of?
What media?
What ratio?
What is the plant growth like?
Is the bottom of the tank clean?
Any picture available would help with a holistic view of the situation.
Sounds like a fundamental problem exists. To lose 4 lots of fish would be soul destroying.

Faye didn't get pic's and he is about 60 k's away,

grow beds are 20 lt plastic containers, GB's have been in 18 months, clay is covered with black good algae or bacteria
Clay Balls mainly and a bit of blue metal
only about 10 x 1/2 x 20 lt containers, water test results are fine
Plant growth is absolutely 0 and he has never had success, even with just carp, this makes me think chemical contamination, but his veggie garden and lawns are magnificent and uses same water, this is what has me confused
Tank bottom is spotless, made sure of that

the time i had probs with rain water was when it was from an old cori tank!!

Nocky, whats the roof made of which catches the rain before it goes into the tank?? It only takes 0.04ppm of zinc to be lethal to trout. Water flowing over about 15 feet of corugated galvanised roofing has been proved to contain lethal concentrations. I lost a dozen or so silver fingerlings earlier this year from rainwater running directly of a galvanised roof into the tank.

Colourbond is ok though

Gav is a tile roof but is an old corry tank that fish are in so maybe getting containment's from tank, but the fact he hasn't been able to grow veg in GB's is a worry

Did he ever manage to cycle the system up? Get through the ammonia and nitrite spikes? How long did each batch of fish survive before dieing off? Was it ever cycled fishless, if so what ammonia source was used? Is there any treatment of the scheme water?

I will guarantee you Nocky that his fish are dying from Zinc poisoning. His plants will be doing crap because of zinc overdose, locking out other nutrients, and a lack of Nitrates.

No TC as fish die in a few days, before any cyccling can happen
OBO I agree, spoke with Faye on weekend and is the only thing we can come up with, you may remember my first corry tank system, I gave him that tank which fish died in as well, but this we think was because he used muddy dam water that is possibly contaminated with chemical

Hi Nocky,

the 20ltr drums used for g/beds are they old farm chemical drums or food grade drums?

God bless froggo.

When you say corry tank, do you mean corrugated galvanized metal tanks? If so, then yes I expect the problem is the tank and associated zinc levels. Remembering that pH plays a big role in zinc and copper toxicity, Very high pH water and one might keep critters alive in such a tank much longer but as the pH comes down, much more zinc is mobilized and becomes more dangerous to fish.