Why are my fish dying if my water tests fine?

[clmags19]

I have 2 tanks and i lost a fish in 1 two days ago and lost a fish in the other today, i also lost a fish about 2 weeks ago in the second tank as well. My ammonia and nitrites ar zero ph is 6.8 and nitrates are 20ppm in the tank where ive lost 2 fish.....this all seems normal to me. Im testing my other tank now but last week when i tested it was all fine. What else could be happening?

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[clmags19]

My second tank ammonia and nitrites 0 nitrates 20ppm and ph 6.4....is ph too low? Alson i noticed last time i did water change the bio filter was coming loose at the top. Should i maybe change my filter?

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[gilpi]

Not knowing the history behind the fish (where they came from, how long have you had them) and other factors makes it hard to tell why your fish are dying.
Disease and stress could be a cause.

 

[clmags19]

Hmmm well the last one i bought was over 2 months ago. And i dont know how to tell if they have diseases?

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[Coyne]

Knowing your water parameters won't always tell you why a fish died. In fact, in an established tank your likely going to have stable readings.
It is, however a good idea to get a reading when a fish dies because it's a fast, easy way to make sure the water parameters are good and rule it out as a suspect (or, if they're bad you can fix it before it gets worse).
Plenty of other things can kill a fish besides poor water quality


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[Deminox]

Are all the fish coming from the same pet store, and does that pet store seem to have an unusual amount of "sick" tanks? I used to get my fish from one place, they never lasted. Noticed how there was always half the tanks in "treatment". I go to a much better place now, they almost always have a treatment tank, its unavoidable, but they have far less fish in them, and they have a much larger quantity of tanks over-all. So the ratio of sick to healthy tanks is far better.

Other issues: if they are lasting 2 months, then they got acclimated. But they could still be stressed. What kind of behavior are they exhibiting? Look up the breed and look up their behavior. Are they supposed to be in schools? Are they mixed with fish that they shouldnt be? (ottocats are timid and will starve to death trying to avoid bossy goldfish) Are they getting enough food? too much food?

Get some details on the species of the fish and the things they are doing.

 

[keegster803]

What is your livestock in your tanks? And the nitrates being that high can help take out the fish's immune system, making them more susceptible to desease


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[Pittenger5]

I had the same issue the other day, I THINK its because my tank got too hot. I'm in texas, so we're hitting 80 during the day, but in the 50s at night .... since I was at work, I never turned the AC on. My tank went from 76 degrees to over 80 in one afternoon. The fish didn't like that, and I lost more than I care to think about.