Backyard Aquaponics
A place to discuss aquaponics

Good morning Abndrew

Firstly- don't lose heart as you will identify the problem, solve it and be the better for it.

NOW- this is where we are going to need the help of other APers.

Your set up is ,if I am not mistaken, a CHIFT PIST system. Could it be that the water is just not flowing enough to prevent pockets of ammonia or oxygen depleted water building up at the bottom of the tank. The reason I raise this ,is because the chap who supplied us with our tanks initially stated that trout needed a good and constant flow of water to swim against to build up muscle and this could best be achieved by having a good flow in the water in a round tank, hence all our water pours in at an angle to keep the flow going.

CHIFT PIST in a square tank may not be ideal for trout but I do know it works fine for our carp but we haven't tried square tanks for our trout.

THis needs the opinions of those on this site to help us forward.

WD may be on to something... Andrew, where do you normally take your water from for the water tests?

It is an interesting point - usually from the top

Not sure how to take a sample from the bottom ?

My concern is that the aeration and flow from the pump might actually be too strong for them. I've got so many airstones in there at the moment that I'd be surprised if there were any deadspots - they move quite a bit of water around. I'll try and take a video.

Thanks for the gee-up WD. Very easy to get depressed on this drip-feeding deaths.

Yep, we're chift-pist on a timer, SLO's taking the overflow from the base and sides of the tank. 16 airstones at the moment ensuring everything stays stirred up.

I'll keep plugging away.

hi there andrew,
thanks for your email pointing me to the post..... wish i’d have known earlier... right firstly it seems your doing the right thing in terms of using salt and also water changes... in my opinion it looks like you had a combined effect of high temperature, low DO and ammonia and nitrite issues early on (from the figures on the first post) sure not off the chart but nitrite is a creeper.......

i think (and it might well be completely wrong) that the situation might be as follows:

i dont think you don’t have IHN, it seems much more likely a combination water quality / toxicity problem from temp-ammonia-nitrite- compounded by low o2 in the early days...

i’m presuming that the gills of the dead fish are reasonably brown and dull (probably even then live fish, which is indicating a lack of oxygen in the blood (somewhat obviously) but most likely a nitrite issue which is compromises the ability of the haemoglobin to bind with O2 (it competes with it), and this is compounded by low O2 either due to lower supply or increased BOD...

the other possibility would be hyperplasia caused by excess ammonia, and causing gills to stick together and therefore harder to take up O2. A sign would be the fish swimming to the surface and then flicking or gulping quickly and returning down again... not exclusive to this but an indication it they are a bit skitish as they are trying to free their gills..

so assuming its just nasty cumulative effects i would recommend the following:
they need clean water fast... dont worry to much it there is some chlorine as this
dont cull, they could recover if you sort the water quality and a good opportunity to use them as markers as to when things have stabilised..
do wanted changes as you have done (careful where u put it will all your fruit trees around!!)
salt (you’ve tried that) and its more a treatment than cure but does work...
more 02, you’ve done that... so see what happens - although maybe best not to stress them in a jacuzzi...
review your solids removal.... square deep tank with lots of corners for wastes to settle wont help with the BOD.. this is something that i noticed welsh dragon point out as well, but its very very true, solid need to be removed efficiently and quickly in any system, not just for anoxic degredation, but also wont help with production of off flavours like geosmin.. and make your fish taste metalic or 'muddy'....

the more i think about the more sure i think its a temp/water quality issue...

possible steps for the future...

Trout outside..... - ok they can grow in higher temps but that water quality and DO needs to be right for that -- if the trout tank were outside then it would have a higher than normal temp due to being integrated with a polytunel.... might be the only way to go if you really want trout..... all of our mini systems that we’re bring out shortly have trout options for greenhouses/polytunnels but all are located outside for that reason..

Carp... always a great one to get started with... and when you’ve eaten smoked carp... who needs trout!! if you want to go this way, give me a call and i can arrange a delivery or organic carp at a range of sizes from our partners Aquavision - an accredited organic facility

as welsh dragon suggested sturgeon and tilapia are other options but certainly on the tilapia front, you’d need heating and from what i remember of your system when i saw it, its not madly well insulated so it might be a bit energy intensive.... what about perch.... they are amazing to eat... they are very happy and grow fast at 20-25degrees (they eat worms allowing directly integration with vermiculture and they taste amazing.....
just an idea... but could feasibly be added in with a few bigger carp??

ok well hope that helped,
stick at it, it would be good to know water quality data for the duration of the events as this would confirm what i thinks happening, but certainly with trout (and we grow millions up here at the institute) during this time of year when temps are high (even outside) the cumulative effects of nitrite and ammonia toxicity often causes trout problems.... and very often, in commercial systems, feed is dramatically decreased during these months often when growth could be greatest...

give me a call any time

07545 817206

best wishes to all, (feeling slightly shameful about my lack of backyard aquaponics inputs..)

charlie

Hi Charlie,

We'll speak later, but for the record, tests have been pretty consistent

O2 has been 12->15+
Temp has been 16<-20c (currently down to 16c)
Ammonia stable at below 0.25
Nitrite always below 0.05

The bottom of the tank at the start of the problem did have quite a bit of uneaten food, that is now all gone. Most of the 5 fish I just pulled out were on the bottom, two of them trapped below the SLOs (one looking like it had been there at least a few days)

Andrew, it is now my common practise that if I detect something is wrong with the fishes (off feed, acting funny or higher ammonia/nitrite reading, I put the system on manual override, no timer. Hopefully you have designed your system to be able to do that. My suggestion would be to constantly run the pumps for a period of time, if anything it would help clear up "dead-spots", create more aeration and probably maintain a more constant temperature as you are not flooding and draining...