I Have Done A Dreadful Thing

[ShinySideUp]

The background details are irrelevant but on Saturday I turned off my filter and forgot to turn it back on. This morning sixteen phantom tetra's and four zebra loaches are stone dead. The only survivor is a cory that was put in this tank because he wasn't doing to well in my big tank (his tankmates were fine though), he was swimming around all the dead fish as if nothing had happened.

I can only assume that as the bacteria died off in the filter they released toxins into the water that killed all the fish. Before I cleared out the tank I did do an ammonia check out of curiosity but it was fine, i didn't bother with any other checks, not really any point.

So now I have an empty tank. All the water is gone, the filter media, gone (I've also removed the internal filter as I shall use an external one on future), and I've also chucked out all the gravel substrate as I'm not going to risk any toxins remaining. So where my fish sat only yesterday, there is a largely empty space.

The cory has had to go back with his mates in the big tank, he was ok this evening.

I shall start another thread as to what filter to replace the internal one with.

I am rather sad and feel more than a little bit stupid.

 

[KkAaNnEe]

Id be really suprised if you lost that many fish just from your filter being off

 

[Staxx]

only for 2 days aswell. i hear storys of a LOT longer.

 

[ShinySideUp]

Id be really suprised if you lost that many fish just from your filter being off

What can I say, it's the only thing that's different. I did wonder though about the age of the filter material; I tend not to mess with it if the flow is ok and as such I suppose there could be a sizeable number of dead bacteria in the media itself that go to provide ammonia in their own right to the living bacteria. Once the living too are dead there is nothing to stop them and the old, dead bacteria from joining forces in a toxic 'bomb'. Just a thought.

 

[KkAaNnEe]

Maybe im missing something but you said yourself there was no ammonia, which I would believe to be what killed the fish, its strange indeed, a shame too.

What do you mean about the age of media? Wouldnt the toxic bomb be ammonia though? Which has been ruled out? Weird

 

[Bugdozer]

Maybe with the filter off the water became very deoxygenated?

 

[ShinySideUp]

Maybe with the filter off the water became very deoxygenated?

Hmm, that's a possibility, I hadn't thought of that. Mind you, the night before the morning I found them dead they were swimming about happily [so why didn't you notice the filter then, you idiot?!!!] so that would be a bit quick.

I don't think I'll find the answer now but hopefully the problem won't arise when I get the tank up and running again because this time I'll be using an external filter and being able to see it will make it unlikely I won't notice it's off.

All credit to Juwel's internal filters though, you just can't hear them -- at all (even when they are on ).

 

[AXIS]

Had you switched off the heater as well?

 

[FishFanatic04]

This doesn't feel right to me. Filter bacteria can travel in the mail for a few days and enough survive to jump start a cycle. Your bacteria should not have died in a day. Oxygen issues are a possibility but also will raise my eyebrows. I use little surface agitation in my tanks as it drives out co2 for plants. DO you have plants Shinysideup? If you have all fake ornaments then I would think it was oxygen.

The heater is a good point if the temp was Extremely off. I drop my temp up to 5 degrees to induce spawning and have read plenty of other people's thread who do the same.

 

[sadguppy]

My initial thought is that the heater malfunctioned and cooked them bottom dwellers are often the ones to survive as heat rises etc...

 

[prankster705]

Nitrifying bacteria die off very slowly. This is unlikely to be the cause of death.

As you've said, ammonia was fine, as is to be expected.

I'd side with dissolved oxygen problem - lack of circulation is a problem when a filter goes; since gas exchange happens only on the surface, without circulation, the water at the surface is not being constantly renewed with oxygen poor water and oxygen rich water is not being constantly pushed down in the water column.

The cory perhaps survived as it might be a warmer water species (warmer water holds less oxygen by default) or just have lower oxygen requirements in general.

 

[TenaciousG_]

I've noticed my fish hate it if I turn my air pump off but I have to at night seeing as I sleep in the same room as my tank I use an internal filter from interpet and I think it is much better than the old external filter I used to have, and the media is a sponge so loads better. Over night i often see them along the bottom, colour drained from lack of oxygen so i guess it would have to be that.

 

[prankster705]

I've noticed my fish hate it if I turn my air pump off but I have to at night seeing as I sleep in the same room as my tank I use an internal filter from interpet and I think it is much better than the old external filter I used to have, and the media is a sponge so loads better. Over night i often see them along the bottom, colour drained from lack of oxygen so i guess it would have to be that.

Fish go up to the surface; where the oxygen concentration is higher in nature, when oxygen concentrations are low. It is natural for fish to lose part of their color at night (I think).

 

[JohnDyer]

I've noticed my fish hate it if I turn my air pump off but I have to at night seeing as I sleep in the same room as my tank I use an internal filter from interpet and I think it is much better than the old external filter I used to have, and the media is a sponge so loads better. Over night i often see them along the bottom, colour drained from lack of oxygen so i guess it would have to be that.

Fish go up to the surface; where the oxygen concentration is higher in nature, when oxygen concentrations are low. It is natural for fish to lose part of their color at night (I think).

Yes, fish "turn off" bright colors when they sleep. It's very obvious in "shiny" fish like neon tetras, the color returns if you turn on the lights.

 

[ShinySideUp]

I think I will have to go with the oxygen depletion as the heater was (is) fine. I especially would favour this explanation because while the Lido is 120 litres it is a very deep tank so the surface area is not huge with that volume.

Thanks for all your replies, I shall be much more careful in future.