Help with tank problem

[freerunner416]

Hi,

Woke up this morning to find that all my large fish ( 3 x discus and 3 x large angels) were all dead. Also dead was a couple of my black tetras.

I have added no fish in over two months. I have a 320litre tank and did a 60litre water change yesterday as normal. The fish were all swimming around fine last night at 10pm and looked great. I didnt do anything out of the ordinary. The fish that survived.... 7 tetras a cory and two plecs are all gasping quite a bit and the tetras are staying at the top of the tank.

The filter, as normal, has quite a lot of water movement. If i put my air curtain on the tetras swim around fine but the minute it goes off they go back to the top of the tank.

Could this be an oxygen problem? Any other ideas?

 

[Slaphppy7]

Did you maybe forget to add water conditioner during the WC?
Do you always match your tap temp to the temp of the tank during WC's?

 

[A Fishkeeper]

where do you live(roughly)? I live in London and we have a problem with our water. I did water change over weekend, lost 3 fish and have 2 others not too well.
Aquarium shop have told me loads of people been losing fish after water changes. Fish shop also lost fish, they said it’s something in the water that not showing on tests.
They told me to put water in buckets for 24 hours before doing any water change to try and not lose anymore fish. Not done water change yet because too scared.
My fish behaved differently to your before dying though so may be different problem ?

 

[freerunner416]

Did you maybe forget to add water conditioner during the WC?
Do you always match your tap temp to the temp of the tank during WC's?

I know its frowned upon but i have never used conditioner.
I don't always match the temp of the water to my tank temp but it only drops 2 deg during water change

 

[Slaphppy7]

"I know its frowned upon but i have never used conditioner."

Well, I'm willing to bet that's the answer to your fish deaths...though I know nothing about the tap water quality/treatment in Scotland

 

[freerunner416]

where do you live(roughly)? I live in London and we have a problem with our water. I did water change over weekend, lost 3 fish and have 2 others not too well.
Aquarium shop have told me loads of people been losing fish after water changes. Fish shop also lost fish, they said it’s something in the water that not showing on tests.
They told me to put water in buckets for 24 hours before doing any water change to try and not lose anymore fish. Not done water change yet because too scared.
My fish behaved differently to your before dying though so may be different problem ?

I live in central scotland. I havent heard of anything wrong with our water. Really sorry to hear about your fish also.

 

[freerunner416]

"I know its frowned upon but i have never used conditioner."

Well, I'm willing to bet that's the answer to your fish deaths...though I know nothing about the tap water quality/treatment in Scotland

or that i have kept fish and discus for over 25+ years doing the same thing with no issues..... just saying.

 

[Slaphppy7]

or that i have kept fish and discus for over 25+ years doing the same thing with no issues..... just saying.

THAT is worth noting....I'd really be interested in seeing your Water Quality Report from your local municipality ...

 

[A Fishkeeper]

I live in central scotland. I havent heard of anything wrong with our water. Really sorry to hear about your fish also.

At least you can rule that out. Thanks, it is so sad when you lose fish. Hope you find cause and prevent any further loss.

 

[Essjay]

Does your water company use chlorine or chloramine? If it's chlorine, do you let the water stand to allow the chlorine to gas out?

 

[Colin_T]

The fact you did a water change yesterday and the fish died shortly after, and the problem has affected the entire tank, would suggest there was something in the new water.

If you don't use a dechlorinator, then you probably added chlorinated water to the tank and that has harmed the fish.

If the water company did work on the water pipes recently, they would have increased the dose of chlorine/ chloramine after the work to make sure there was nothing alive in the water. This compounds the problem of not using a dechlorinator because you add much higher levels of chlorine/ chloramine to the tank.

This is why you should always dechlorinate water before adding it to the tank. You never know if or when the water company is going to do work on the pipes and increase the chemicals in the water.

----------------------
Right now, you should add a full dose of dechlorinator to the tank, increase aeration/ surface turbulence, and add some Activated Carbon to the filter. Then cross your fingers and hope the remaining fish survive.

 

[mark4785]

You mentioned that the fish that survived were gasping which suggests hypoxic conditions (low oxygen). This can be caused where you add a new object such as bog wood or new filtration media that causes a reaction whereby lots of oxygen is used up. Did you add any new objects or filtration media recently?

The other possible cause is a chemical that may have been added into the tap water by your water company.

I think you should do a 80% water change, take any new objects out, particularly if they are dirty and use dechlorinator on the new replacement water.

 

[Slaphppy7]

You mentioned that the fish that survived were gasping which suggests hypoxic conditions (low oxygen). This can be caused where you add a new object such as bog wood or new filtration media that causes a reaction whereby lots of oxygen is used up. Did you add any new objects or filtration media recently?

The other possible cause is a chemical that may have been added into the tap water by your water company.

I think you should do a 80% water change, take any new objects out, particularly if they are dirty and use dechlorinator on the new replacement water.

Gas bubble "disease" could be a third possible cause, if the OP added source water that was much warmer than the tank water temp...it's most important to match source water temp to tank water temp, as closely as possible, during WC's...I learned the hard way

@Colin_T, note post #7 above...the water company would finally dechlorinate after 25 years (???)

I'm a bit confused...

 

[Colin_T]

or that i have kept fish and discus for over 25+ years doing the same thing with no issues..... just saying.

you have been lucky up till now.

 

[freerunner416]

You mentioned that the fish that survived were gasping which suggests hypoxic conditions (low oxygen). This can be caused where you add a new object such as bog wood or new filtration media that causes a reaction whereby lots of oxygen is used up. Did you add any new objects or filtration media recently?

The other possible cause is a chemical that may have been added into the tap water by your water company.

I think you should do a 80% water change, take any new objects out, particularly if they are dirty and use dechlorinator on the new replacement water.

There was no new objects put in but that is really interesting to hear.

I had my water checked at the local fish store and talked through the issue with them. They think that the filter must have stopped working. Or not been high enough. I possibly forgot to turn it back up after the water change. I can’t remember how hard it was running or if it was running when I came down to it in the morning. I did turn it straight up to full.

Thanks for all the suggestions though people