Backyard Aquaponics
A place to discuss aquaponics

It does have anti-caking agents I'll have a look for better stuff next time - should I do a water change?

The good news is that although we lost four overnight, we haven't lost any more today.

Pool salt is often pure sea salt...

It's not as easy to find a pool shop here as it was in Brisbane I'll have a good look though.

Andrew, when we see you we will give you the details of the right salt and where you can get it from. It works out about £20 for 20 Kg. Lasts us for ages.

WD and OH

Thanks! there are a whole heap of questions I have for you - some of which I've had to find answers for over the last few days.

Fish deaths seem to have stopped now though, and we should still have 74 fish in the tank, so it could be worse.

Damn. Four more dead overnight. Considering a full (ish) water change, although the water is sparkling and clear now (after couple of days of looking really cloudy due to the action of the new aeration)

Is it just the same problem working through? The dead ones are coming out with swollen gills again, so looks like the same symptoms.

The remaining fish seem to be active - swimming, jumping etc. Was just considering feeding them again this morning when I found the four overnight casualties.

Don't feed for a while. I suggest at least 4 days after your last death.

Swollen/red gills is an indication that they are affected by either high Ammonia and/or Nitrites. Considering that you have done a water change this may mean that your bacteria may not be functioning as well as expected.

Alternatively it could be a reaction to the salt. Personally, I am against salting a fish system. I know a lot of APers do it. But for me, it has never sat well. I would give the Koi an occasional salt bath when transferring them between tanks (a 10 second dip in a high salt solution) but never had salt in the actual fish water directly.

It sound like your initial problem stemmed from the rise in your tank temperatures, which led to a lower tolerance of the ammonia in the system. The deaths would have released higher concentrations of ammonia into the water. Check the bottom of the tank for any dead ones stuck down there. I would also see if you can increase the oxygen flow rate and possibly the water flow rate to get things running through the system a little faster.

Are you using screened overflows to your growbeds? Could a tiddler have been sucked into one and be stuck in the pipes?

Yes don't feed for a few days... I was either once told or read before that some of the fish deaths experienced after the initial event are fishes that were meant to die as well but just delayed for a few days... these fishes may have been traumatised as well but not healthy enough to recover hence a slower death....

Thanks guys, I'll hold off feeding for a while.

Ivansg - that's my feeling on the fish, they're the ones that just haven't recovered, there's certainly plenty of air in there now for them.

DragonC - we haven't had a high ammonia or nitrite reading at all,just that low oxygen reading. There are so few fish (relative to the system size) that that shouldn't be a problem unless we kill all the bacteria. All the overflows are screened, and have 5mm holes, so I'm assuming nothing caught in the m, but will pull them apart and check.

I haven't done a full water change yet - don't want to mess around with any more factors at this stage, but I'm seriously considering it.

Just went down for another check. Three more dead, two floating upside down at the surface breathing really fast.

O2 level is about 12, water temp just over 20. Guess it's just a case of watching and waiting.

OK, officially not past the worst, just puled another three out, and there are at least four more floating upside down.

From watching some of the patients and doing my Amateur Vet bit, I think there must be some infection involved. I can see some of them floating upside down one minute, then managing to get themselves upright for a quick dart through the water, and then, seemingly reluctantly, returning to being belly up. I've added more salt to take the system above 1ppt, but it might all be in vain - here's the "google diagnosis":

Infective Haematopoietic Necrosis (IHN) - Virus - Erratic swimming eventually floating upside down whilst breathing rapidly after which death occurs; eyes bulge; bleeding from base of pectoral fins, dorsal fin and vent

Haven't seen the bleeding, but will have a look at the next corpse. Apparently the treatment is - get rid of all the fish. Unless it came with the original fish, the only other vector is perhaps the Water Chestnut plants I bought from the local Aquatic place?

Any thoughts?

OK, three more dead yesterday evening, another 7 gone by this morning. That makes 45 dead out of the 100. Now resigned to losing all of them.

As I'm still not sure what has done it. What's the best way to clean the system before putting more in?

1. Full water change
2. drain and check for any foreign objects in the system - particularly anything metal
3. scrub and clean with something fish-safe? How do you clean the gravel? Do you need to?
4. only put Carp in to give us a chance.

Maybe the dishwasher salt was not suitable for fishes.

Anyways, have you tested your water again?? What are the results?

I suppose there is no harm to do a 30% water change and see if it helps, but do it gradually especially if the temperatures in the tank is quite a bit different to tap/bore water temperature.

Thanks Ivan.

Haven't tested this morning - O2 was over 12 yesterday, Cl was at 0.

I'm off to see WelshDragon today, so will have a look at gentle water change this afternoon.

Are the fish slimy to the touch? If so then it's a water issue. If not then it's probably an internal bacterial or viral issue.