Emergency: Healthy Tank, Fish Died

L

lkunz

Logan & Linds
Oct 29, 2003
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Virginia
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We have two aquariums, a five gallon and one ten gallon, both of which have seemingly non-toxic water. Here are the stats for both -

5 Gallon:
Ammonia 0, Nitrite 0, Nitrate 60 ppm

10 Gallon:
Ammonia 0, Nitrite 0, Nitrate 60 ppm

Both have finish cycling within the last month and have not been overstocked. Yesterday, we added a new heater into each aquarium. The type of heater is a Marineland Dual Temp 5-20 100 Watt Precision Submersible Heater.

Today, as we went to feed the fish, we discovered that all the Tiger Barbs in the five gallon tank are dead. In the ten gallon, two of the Red-Eye Tetras are dead. The rest of the fish in the ten gallon are lethargic, but did eat when fed.

We installed the heaters as a precautionary measure for the upcoming winter. It does not appear that they even turned on overnight. Could there have been toxic chemicals on the heaters that caused the fish to die? If so, and any toxins are in the water, what do we do now? If you do not think this is what happened, please shed some light.

Thank you in advance for any advice you can give.
 
60ppm for nitrates is a bit high I think. I'm not sure if that would kill fish like that but I've been under the impression that you should shoot for under 20ppm for nitrates and get that by doing regular water changes.

Do you have thermometers on the tanks? You should have one on the opposite end of the tank from the heater. The fish should be able to take a bit of a range in temps but if the heater was set too high or was defective that could have had something to do with the deaths.

Have you added anything recently? Decorations? Meds?

Definitely do a good water change. Probably 20% to get those nitrates down.
 
I always wash everything before it goes in my tank. It is possible there was something on the heaters, but it seems unlikely. You may want to check the heaters for cracks, which could be releasing electricity into the water. Unplug the heaters before reaching into the tank--many people can confirm that reaching your hand in is a nasty way to discover a cracked heater.

How long had the fish been in the tank? Could be they were suffering from an ailment when purchased. When was the last water change? The nitrate levels are pretty high for both tanks. While nitrates themselves are seldom toxic, they are an indication of other waste products that we can't easily detect. Regular water changes to keep the nitrates in uplanted tanks below 20 ppm are a good idea. If the fish were a recent addition, the high levels of these other toxins could be responsible for their deaths as well.

While not the cause, 5 tiger barbs in a 5 gallon tank is a high fish load, and too small a territory for these fiesty little guys. They need more space to avoid being stressed.
 
Thank you both for the input. Three of the tiger barbs were purchased on Friday, so we returned them to the pet store. The manager also said to check the temerature, and it is steady in both tanks at 78 F. The ten gallon tank is moderately planted, and the five gallon is mildly planted. This creates low alkalinity which we sometimes increase by using kH up. We have not done this to either tank in over a week. Otherwise, we have not recently added any decorations or chemicals to either tank.

The five gallon originally had Red-Eye tetras, used for cycling, that have been moved to our ten gallon. The five gallon has been cycled for two weeks and the Tiger Barbs have been there for three. Our last water change for both tanks was on Friday. In the five gallon, we did change the filter cartridge for our bio-wheel filter (not the bio-wheel itself). Could that have contributed to their deaths?

The five gallon was intended as a temporary living situation for the tiger barbs. We are getting a bigger tank within the month in which to transfer them. Our biggest concern is what to do now. Obviously, the water is unsafe for fish to live in. Do we need to do a complete water change, rinse the decorations, and start over? Or do we need to wait it out and then add more fish? If any undetectable chemicals have gotten into the tank, how can we get rid of them?

We do regular water changes to keep the nitrate levels down. Is there any thing else we can do to bring them down? Thank you for any additional advice.
 
More frequent water changes will help reduce nitrates, but if these are planted tank, I think it's odd that the levels are so high anyway. My planted tanks show 0 nitrates, even with fertilization. You may want to have your water tested by a different kit, just to confirm accuracy.

Since there was a recent addition, it could be that the fish introduced a pathogen. If this is the case, leave the tank without fish for a week (you'll need to feed the bacteria with ammonia) and run carbon. Carbon will remove most chemicals within 2-3 days.

Did you rinse the filter media prior to putting it in? If it's one that has carbon, the dust should be removed before use. This dust can accumulate on gills and impair the fishes ability to get oxygen from the water.

By replacing the filter media, you did remove some of the beneficial bacteria. It should not have been significant enough to kill the fish, especially since the ammonia still tests at 0.

The red-eyes could have succumbed to the ammonia/nitrite burns they suffered during cycling. The damage caused by exposure to high levels of ammonia or nitrite is not always immediately fatal, but kills them down the line.
 
Tank temp before heaters?

What was the tank temp before adding the heaters?

A rapid change in temp could have done it. I've read that tank temp changes should be 2 degrees per day, but don't know what increase might be fatal, certainly it would have to be far more than that.
 
You are using pH up...

I recommend against using any of the Up/Down products unless you have some very unique circumstances...generally, all it causes are pH swings that can affect the fish (especially if your tap water is drematically different from the water in the tank).

Thanks,
Steve
 
re:

The temp. in both tanks was 80 yesterday (before the heaters) and is at 80 today. We rinsed the heaters before we added them to the aquarium. The heaters only turn on if the temperature gets too low. We added them because the weather has been cooler at night. The last 24 hours have been warm, though, so the heaters should not have kicked in at all.
Our filter cartridge contains a sponge and activated carbon. We rinsed the cartridge thorougly in cold water and then saturated it in dechlorinated water before adding it to the tank's filter. Are there any other precautionary mesaures to take when switching filters?

All the barbs in the five gallon died. There are two plants in this aquarium and several in the ten gallon. It is my understanding that plants will eat alkalinity (kH), but that low alkalinity can agitate/stress the fish. We were advised by our local pet store that there is no natural way to increase the alkalinity, which is why we have been occasionally adding kH up. We do not use pH up or down and try to avoid chemicals as much as possible. In the ten gallon, one of the fish that died was the smallest Red-Eye but not cycled in the other tank. All the other fish in the ten gallon (Red Eyes & one Black Skirt) are not swimming much but usually do not this time of day. None are breathing erraticaly or show any other strange behavior.

As far as the nitrate levels, the pet store tested our water sample when we took three of the barbs back. We will continue to do water changes and may get another test kit to determine if ours are testing correctly. Also, how can I feed ammonia tothe bacteria in the next week or so (while the tank is empty)?

Thanks again.
 
Regular water changes should be all it takes to maintain the hardness of your water. Plants can deplete the water of certain elements, but this takes time and no water changes-longer than your tank has even been set up. There are other ways to stabilize kH, but for most tanks regular water changes will be enough. I recommend you monitor the kH on the tank for one month, then determine if any treatment is needed. What is it reading currently? What does it read from the tap?

Rinse filter media in the old tank water, or dechlorinated room temp water.

Add enough straight ammonia (yes, the bottle stuff sold as a cleaner) to read about 1-2 ppm on your test kit each day. Can't do this with fish in there, but it will keep the bacteria alive. This is 'fishless cycling'--meaning no fish are ever exposed to toxic levels of ammonia.

Sorry we can't really specify exactly what killed the fish. There are many possibilities and little to go on.
 
In the interest of covering all the bases, what product did you use to de-chlor the water/filter?

Thanks,
Steve
 
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