Backyard Aquaponics
A place to discuss aquaponics

Help! Can someone tell me why my trout are dying? I'm losing one or two a day. ph 6, nitrites 0, nitrates 80, ammonia 0.25. I have noticed sometimes my trout gasping on the bottom of the pond but aerator seems ok and didn't have these problems last year. I have two 1000 litre ponds each with two 500L grow beds Occasional deaths happening in both tanks. Flood and drain,

Sometimes although pH is reading 6 it may be much lower. Shell grit can be added, it acts slowly and safely.
Eco rose will bring the pH up but add in small increments so as not to change too rapidly.
Salt at up to 3 parts per thousand eg pool salt 3 kg per tank can help too.
Any signs of disease Geedee?

Thanks for the advice Faye. NO evidence of disease,thats the frustrating part,i was thinking about the low ph,i will add some shellgrit and see how it goes

salted? also we have had some rain. do you top your system with collected water?

yep,i top up with rainwater .I don't know what the salt level is at the moment.I added too much salt during summer and the veges suffered so I will have to invest in a meter to measure salt levels. Any advice on what to buy. Thanks for the input Ferozaj

Kinda looks like 02 issue with gasping mouth. What aeration do you have, temp and stock density?

I have the aerator sold by byap Charlie.I did have 20 trout per tank 1000 litres each.Temp I guestimate at around 16 degrees.lucky if I have 15 trout left.

i just have seen before people topping up with rainwater collected from roofs etc if there are chemical traces or leftovers on the roofs it gets dragged into the water

80 nitrates is pretty high, I would say this is part of your problem. You need more plants or to do a partial water change. I am just getting into aquaponics but have been keeping fish for years. Any time I see nitrates over 40-50 the problems start. Even though nitrates are not necessarily deadly to fish, they can be at high enough concentrations. In my experience some fish will be affected by levels as low as 20 , while others will show no apparent symptoms until levels have reached much higher levels (100+), however immature fish will begin to be affected at much lower levels.

Here are some symptomes to look for: Loss of appetite, Fish become listless, Fish experience loss of equilibrium, Fish lay at bottom of tank, Rapid gill movement, Fish curl head to tail (advanced stages)

If nitrates have risen slowly over time, it is not unusual for only one or two fish to exhibit symptoms initially. If nitrate levels are not reduced, more fish will show symptoms. Eventually fish death will begin occurring over a period of a few days to a few weeks.

Just something to think about....

What is your roof made out of?

thanks for the input guys. Last year my nitrates were higher and the trout and veges did fine.Our roof is of tiled construction.I thought rainwater collected from here woud have to be a lot safer for fish than the water coming out of 100 year old pipes from our low dams.

Hiya Geedee, our tap water isn't coming from dams anymore... It is however good quality still. Do you drink your rainwater? My ph has dropped to the low 6's too, noticed it cos the fish have gone off their feed. Added shell grit.
Photos of system/aeration?

What was your PH at last year? What is the minimum reading level of your test kit? Or I could be way off as I just read at " http://www.senasa.gov.ar/Archivos/File/ ... -trout.pdf " that survival is possible at PH 4.5 . You might look over that document at some of the poising (section 3.0) It advises checking source water. If all you have done is "top off" evaporation will begin to concentrate any pollutant in your water supply. Good luck! Keep us informed.

I'm very happy with my PCSTestr 35, it shows the salinity levels changing due to evaporation and rain water additions quite well. It also measures pH, conductivity and TDS.

Or you could buy a $30 ATC Salinity Refractometer off eBAY...