Danios dying, why? - Tropical Fish Keeping - Aquarium fish care and resources

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post #1 of 13 Old 06-09-2011, 12:05 PM Thread Starter
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Exclamation Danios dying, why?

Ok, so I have a 36 gallon tank that went through a fishless cycle. I have had it running with fish for about 3 weeks now. There is only a school of 6 danios in there of the glofish type. First, 1 pink fish died a little after the first week when there were only 3 danios total. I think it was getting bullied a little and was scared to eat. We replaced it and an orange danio just died today (the third week). It had been swimming towards the bottom of the tank and not typically with the school, so we were a bit worried about it the day before. Anyway, now there are 5 fish in the tank. I tested the water and here are the results:

ammonia: .25ppm
nitrite: 0ppm
nitrate: 5-10ppm
ph: 7.8

Well I realize the ammonia is not 0ppm, so is that the problem? I wasn't sure if that was enough to kill a fish. If so, what actions should I take to lower the ammonia level?

Also, the ph is 7.8, which is a bit high, but that is just the level of our tap water. I'm not sure if I can do much about that if it is the problem.

Lastly, the temperature is about 80 degrees F. That is on the higher side, but I do not think there is much I can do about that either since it is summer and that is room temperature.

Please help me identify the problem and any suggestions for solutions are greatly appreciated. I do not want any more fish to die in what should be an established tank. Thanks in advance!

Last edited by paige17; 06-09-2011 at 12:07 PM. Reason: typo
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post #2 of 13 Old 06-09-2011, 12:27 PM
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Firstly, the tank was not cycled, or you added fish too fast. In a newly fishless-cycled tank, I would add one fish every two weeks to be safe (unless you have plants).

The puzzling thing to me, is that in higher PH water ammonia turns to Ammonium, which shouldn't kill a hardy fish like a zebra danio..

The temperature is quite high, but again. Alone, that shouldn't kill them. It may be the sum of everything working together, like the phrase 'the straw that broke the camel's back'.

You should really find fish that can handle the temperature that the tank will be at. Danio's will never thrive in warmer temps. Fish can't control their body temperature like we can, so their metabolism speeds up in warm water stressing them greatly.

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post #3 of 13 Old 06-09-2011, 02:38 PM Thread Starter
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Ya, I think I must have added fish too quickly because I'm pretty sure it was cycled. Oh and that is helpful information to know about the temperature. I think you are probably right about it being everything together. Thank you so much for your quick feedback!
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post #4 of 13 Old 06-09-2011, 03:10 PM
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Anytime.

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post #5 of 13 Old 06-11-2011, 01:15 PM
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The puzzling thing to me, is that in higher PH water ammonia turns to Ammonium, which shouldn't kill a hardy fish like a Zebra Danio..
You got this reversed; ammonia remains ammonia in basic water (pH above 7) but changes to the harmless ammonium in acidic water (pH below 7). This was obviously just a slip, I know that you know this. But I wanted to clarify it for paige17.

Ammonia above zero should be investigated as this will have detrimental effects on fish. Have you (paige) tested your tap water on its own?

Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #6 of 13 Old 06-11-2011, 02:10 PM
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For what it's worth, I've had similar bad luck with the glofish/danios even though they're supposed to be a tough fish.

I lost over half a dozen in a well established tank with higher PH and excellent water quality for no apparent reason. (I still have one left, and he seems to be doing just fine.) In the same tank, I have a small school of neon tetras that have been thriving for over a year, and yet they're supposed to be more on the fragile side.

Each tank tends to establish different dynamics. Sometimes it just boils down to finding out which fish do well in a given tank.
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post #7 of 13 Old 06-11-2011, 02:29 PM Thread Starter
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Oh I just checked for ammonia in our tap water and it is .25ppm! Looks like we've found the problem, thanks. What should I do now since I have a bad source?

And thanks Ashcan Bill for you feedback too. I was wondering why a hardy fish would die so easily.
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post #8 of 13 Old 06-11-2011, 02:53 PM
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First comment on fish hardiness. Ammonia and nitrite affect all fish. Some succumb almost immediately and die, others "appear" to manage. But regardless of that, they have been internally affected. This can frequently show itself down the road, sometimes weeks, sometimes months; more health issues than otherwise, and almost always a premature death. No fish should ever be used to "cycle" a tank. There are safer ways.

Another comment on hardiness, is that generations of tank-raised fish often become much weaker than their wild counterparts due probably to inbreeding. And add to this, the Glofish is a genetically modified Zebra Danio. This fish has been banned by the European community, which indicates what they think of such practices.

Now to the tap water ammonia issue. You should get a water conditioner that detoxifies ammonia. Many--but not all--do this. This handles the initial influx of ammonia at a water change. Conditioners normally are effective for about 24 hours. By this time, the bacteria/plants in the aquarium will be able to handle any ammonia remaining.

Ammonia detoxifying is almost always achieved by changing the ammonia to relatively harmless ammonium. Bacteria and plants use ammonium/ammonia so nothing is affected. Test kits read ammonia/ammonium as "ammonia" so a test will still show it, even though it will be the harmless ammonium.

Byron.

Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #9 of 13 Old 06-12-2011, 12:04 PM Thread Starter
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Thanks for your comments about hardy fish, it is helpful information. Also, I'm so glad I can just have an ammonia detoxifier instead of buying that water they sell at the pet store. If I just did a water change yesterday, should I do another one today with the ammonia detoxifier, or just wait for my weekly change? And thanks so much, if it wasn't for you I wouldn't have realized the ammonia was from the tap water or what to do.
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post #10 of 13 Old 06-12-2011, 12:13 PM
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Quote:
Originally Posted by paige17 View Post
Thanks for your comments about hardy fish, it is helpful information. Also, I'm so glad I can just have an ammonia detoxifier instead of buying that water they sell at the pet store. If I just did a water change yesterday, should I do another one today with the ammonia detoxifier, or just wait for my weekly change? And thanks so much, if it wasn't for you I wouldn't have realized the ammonia was from the tap water or what to do.
This tank was cycled, and has had fish for 3 weeks post-cycle. Ammonia is from the tap water. By this time, after a day, I would expect the bacteria to have handled it. Observe the fish; any signs of red gills, faster respiration, close to or hanging at the surface or gulping air...do a water change immediately with a conditioner that detoxifies ammonia.

Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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