Urgent advice needed Fish Keep dieing suddenly

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Urgent advice needed Fish Keep dieing suddenly

Postby teddybear154 » Wed Jan 15, 2014 3:06 pm

I have a 200L Tropical fish tank. It has been set up and running for nearly 3 year so is not a new set up. It is a planted tank with quite a lot of plants,coconut shells and bog wood.

I use a very large external canister filter.

At the beginning of last year we had a long power cut that lasted several days. Unfortunately nearly all fish died because of this. Only my 2 plecos and a pearl Gourami survived amazingly.

Over last year we slowly worked at sorting out and restocking tank. We slowly added fish. By end of last year we had the following in tank.

One pearl gourami, 2 pleco, 6 neon tetra, 6 platies, 2 honey gourami and 4 coridoras cat fish.

A few weeks ago my husband added 6 zebra danios to finish it off. Since adding the zebra danios we have started to notice that fish are dying or going missing. We have lost one coridoras cat fish, 3 platies, and 1 tetra. Then yesterday we found one of our large pleco cat fish that we have had for about 3 years dead.

No fish have shown any sign of illness or disease. They are swimming around absouloutly fine One day then dead the next.

The latest fish to die my pleco had a tiny bit of blood on one side and I noticed a lot of holes in top fin. It did not look like fin rot or any thing like that.

I tested water when found pleco dead yesterday using API liquid tests.

PH 7. Ammonia 0 Nitrite 0. Nitrate 40

I did a large water change after removing dead fish and tested water again today and results today are

PH 7. Ammonia 0. Nitrite 0. Nitrate 5

Each time a fish has died water tests have been simular.

I do regular 25% water changes every week.

Could a dead fish cause the nitrate spike what could be causing my fish to die so suddenly.

Could it be possible that the zebra danios are attacking and killing the other fish. I have read about a few people online having this problem.

Most of the time the zebra danios seem to swim around peacefully, but I have seen them chase other fish occasionally.
I have not seen much aggression during day but maybe they are at night. Fish keep dying at night.

Any advice would be much appreciated as I'm really worried about loosing any more fish.

Thanks in advance
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Joined: Tue Jan 14, 2014 7:47 pm

Re: Urgent advice needed Fish Keep dieing suddenly

Postby Carylnz » Wed Jan 15, 2014 7:43 pm

I think it more likely the nitrate goes up when a fish dies, not before, and not causing the deaths.
As the problem started after adding the danios, I would suspect them. They may either be infected with something, or they have something they have built an immunity to but the other fish have not. I doubt they are killing the other fish, especially corys or plecs.
At this point I think the only thing you can do is wait and see which fish survive the outbreak of whatever it is. If there are no other symptoms, clamping fins, getting thinner, change in behavour etc that points to something specific I am not keen on suggesting medication (and no nothing about various meds as many are not available in my country).
You could try removing, or separating, the danios. If they are killing fish this will stop. If they are infected with something it is probably too late.
My home forum is The NZ Fishroom http://www.fnzas.org.nz
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