I Woke Up This Morning And They Were All Dead

[tintin]

This is awful.

This morning, I looked into my 210litre tank to see nothing but cloudy water. And I mean cloudy. I could barely see a few cms into the tank. Then I saw dead fish floating in the water.

After 3 sets of water changes (totalling about 75-80% changed), I have, in the space of 8 hours (as they were all fine last night), lost:

1x Pyjama Catfish (so upset about losing him)
1x Large Angel fish
1x Large Keyhole Cichlid
1x Curvicep Cichlid
2x Black widow teras
2x Phantom tetras
4x Neon tetras
4x Rummy Nose tetras
1x Male guppy

- Some of these fish I've had for nearly 2 years since I started keeping fish.

I have left:

2x Black Widow tetras
2x Silver Hatchets
2x Male guppys
2x Pearl Gouramis
3x Corys
1x Shark catfish
1x Curvicep Cichlid (not sure if he's going to pull through)

Apart from the cichlid, all the others appear to be breathing ok and seem unaffected.

I should have done a water test before I started changing the water but I panicked. These are the stats AFTER the 75-80% water change:

Nitrate - 25mg/l
Nitrite - 5mg/l
General Harndnes - >6d
Carbonate Hardness - 10d
ph-value - 7.6

So, I need to ask: What could have caused this? What could have killed so many healthy fish so quickly and why have some not been affected?

The water is still a little cloudy but no way as bad. Given the amount of water I've changed already, should I change anymore today? Is there anything else I can do other than sit and wait?

Please, I need help.

TT

 

[kha]

oh dam i feel sorry for you that happened to me once i lost 6 guppies,1 sucking fish,1 gourami and 5 serpeas well hope you get new fish hehe

 

[mark7616]

If you have changed 80% of water and you nitrite is still that high i would be pretty sure to say that has caused it you will need to work out what has caused that spike how old is the tank etc etc.

 

[tintin]

Mark, I thought the same when I saw the Nitrate reading. But it still doesn't make sense.

The tank has been established since the end of November. No new fish have been added for a couple of months.

I cleaned the tank yesterday morning as I do every Saturday. The fish were fine all day. I went to bed around 10.30pm and put in some bottom feed for the catfish as I do every night. No sign of any problems then. No one else has access to the food.

I'm totally at a loss.

 

[Tolak]

Were those water test results from after the first large change, or after the series of 3 large changes? How often have you been doing water changes before this occured, and how much water have you been changing? Depending on the size of some of those fish, it seems to be somewhat overstocked, but not incredibly so.

I could see two situations causing this. First would be some sort of foreign toxic substance getting into the tank and either affecting your bio filtration causing these spikes, or poisining a couple of fish, with their death and subsequent deterioration causing these spikes along with the bacterial bloom. Any sort of exterminator spraying for bugs, carpet or upholstery cleaning, painting, or other activity that would cause airborne fumes or toxins could cause this.

The second would be old tank syndrome finally coming around to bite you in the rear, those are some pretty high readings on those test results after such a large water change.

I would continue with large water changes daily, since you have already started to do so.

 

[tintin]

The test results were taken after the 3rd set of changes.

I do approx 25% water change and vac every Saturday morning without fail.

Just about all the fish had reached their full size. I hadn't intended getting any more as I considered the tank to be fully-stocked.

Your first suggestion is interesting as we have been using carpet cleaner the last few days - though not in the room where the tank is. Whatever poisoned the water would have to have been airbourne.

I've not heard of old tank syndrome before. What is that exactly?

Would you suggest any further water changes today or should I leave it until the morning?

 

[tintin]

The remaining Curvicep looks a bit better now. No further casualities since 1 of the male guppies at about 10am.

I took the filter media from my 20litre tank and squeezed its contents (above the water level) into the big tank to transfer some good bacteria.

Anything else I can do today or do I wait until the morning?

Still feeling rather numb from the whole experience...

TT.