Toxic chemical in tank...

Dmaaaaax

Prolific Poster
Jan 9, 2009
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Trying to solve a mystery. I have a 75 FW tank that has been setup for over 2 months. I have had all my community fish in there for around 2 months. I recently decided to order some Discus, SAE, and some more cardinals for the tank. The shipment came on Thursday. The fish were placed into the tank and each bag was acclimated slowly.

*I did not have a quarintine tank setup at the time because the Discus were essentially the fish I was worried about and wanted them in the main tank. Anything from this point on would have been quarintined.*

The Discus were stressed and appeared to be loosing their slime coat so I added more Prime to the tank and also some aquarium salt. The salt I added was a fairly small amount compared to a normal treatment (1/4cup vs 1 cup). I used less due to plants in the tank but I felt the need to help the slimecoat on the Discus mildly. A few cardinals died that night but I chaulked it up to stresses of shipping. I decided to do a 25% water change to be safe.

However, the next day 16 of my 20 cardinal tetras were dead as was 1 Discus! They remaining 4 were at the top breathing heavy like they had ammonia poisoning, but the test kits showed 0 for ammonia and nitrite. I turned down my CO2 which was not pumping out that many bubbles per second to begin with. I removed the 4 remaining cardinals and put them in a bucket with fresh tap water (Primed) and immediately they looked better. This led me to believe that it is definately a chemical poisoning the fish in my tank, not a disease and the cardinals are just the most sensitive.

Could the salt cause some reverse osmotic conditions in a particular plant to release something toxic to fish? I do not own any exotic plants just your standard LFS types. The only other thing I could think of was that 2 days prior to my receiving the shipment of Discus I decided to clean my tank and move some plants around. I had an anubis nana that was covered in spot algae and some hair algae. I removed it from the tank and one end smelled rotten. I cut that end and dipped the leaves in a mixture of H202 and water for ~1hr. I rinsed it with water and placed it back in my tank. Since the incedent, I have removed this plant...just in case it was leeching something into the water.

I did a 25% water change after seeing the cardinals breathing up top, and another 50% change the next day after finding most of them dead. The 4 I moved to the bucket are all doing fine. The other fish were starting to look stressed, hiding, ocassionally breathing at the top...etc. They would look normal for awhile, eat and then go hide. I decided to break down the 75g tank and moved everything to freshly setup 20g tank. I moved a few plants over, and one of my filters.

24hrs later they all look normal. Colors are bright, they are swimming normally and even the 2 surviving Discus are starting to eat. WTF happend to my 75g?! Here are my guesses:

1.) H2O2 plant reaction w/ or without help from aquarium salt (reverse osmosis).
2.) Some fungus remaining on driftwood became toxic...at just the right time...not buying that, but throwing out the driftwood since fungus has not settle even after 2 months.
3.) Something toxic on the outside of the fish bags that were placed in the tank to acclimate. I never even thought of rinsing off the outside the bags before putting them in my tank. Or from the newspapers they were packed in, heat packs...etc.
4.) CO2 even though I trimmed it and aerated with various water changes? I did switch from having the CO2 on 24hr on a pH meter so it would turn itself off once it got to 6.2 to having a timer added so that it was off ~10hrs at night about a week ago. CO2 just does not seem likely especially with multiple water changes.

Any thoughts, ideas, comments, or other insight would be appreciated. I am using this forum as my therapy session. :eek: From now on all bags will be rinsed and fish put into a Q tank. Lesson learned but mystery not solved!
 

Dmaaaaax

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Jan 9, 2009
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I may have found out my problem. Has anyone else ever heard of this? Someone had a similar problem at another site and a guy posted this as a possible cause. Since I was setting up a Discus tank, I was warming up my tap to about 84F before adding it directly into a tank with prime.

I've seen this happen before, and prime wasn't always associated with it...winter was. In warmer times of year, we don't have to temper the cold water with hot before adding it to the tank; only in winter do we have to do this, when using tap water. Hot water contains less oxygen than cold water. In a tank-type water heater, much of the oxygen in water is driven out of solution by heating it to 120F (avg. thermostat temp setting of water heaters). When we put this oxygen-depleted water into our tanks, it takes a while for it to reacquire its dissolved oxygen. This is why the fish aren't gasping two days after a water change, just in the first 24 hrs following one. So, prior to a water change, the movement of water in the aquarium maintains an amount of dissolved oxygen sufficient for the fish. When we drain 50% or more of this water and replace it with oxygen-depleted water the fish feel it immediately and respond right away. This is another arguement for keeping relacement water in holding vessels for at least 24 hrs prior to a partial water change.
PLEASE HELP Fish Gasping for air - HoustonFishBox
 

SuperColey1

Guru Class Expert
Feb 17, 2007
503
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Lincoln, UK
In tanks with good surface turbulence is this effect still the same? I have been mixing hot and cold to get closer to the actual tank temp recently but can't recall any adverse reaction!!!

Is the surface turbulence negating this problem?

AC
 

Dmaaaaax

Prolific Poster
Jan 9, 2009
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SuperColey1;33919 said:
In tanks with good surface turbulence is this effect still the same? I have been mixing hot and cold to get closer to the actual tank temp recently but can't recall any adverse reaction!!!

Is the surface turbulence negating this problem?

AC

I had a good amount of surface turbulance as well. I had a Fluval 305 and a Magnum at the surface. I think the size of the hot water tank (how much was stored warm) has something to do with it, how much warm vs cold water you used (temp 75F vs 85), and the type of fish you have. My cardinals were definately more sensitive to it than my ram or angelfish. Plus once I saw the breathing problems, I probably made it worse by doing more water changes, so you might not see it unless you do multiple changes within a short amount of time.

In the winter time depending on your location, you may also be using more warm water to get to the target temp because your cold water is colder than normal. I thought I was doing a good thing by testing the water temp and trying to get it close before adding it to my tank. I had heard that Discus were more sensitve to temp differences than pH differences....now I find that this could have been the cause for all the deaths. :(
 

tinkerman

Subscriber
Dec 8, 2007
126
2
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Moorhead,MN
What is in the filter, any ammonia chips ect...? Thats a lot of salt to add at one time. If you had ammonia chips or some other stuff the salt would have released it as the recharging instructions. Just throwing out an idea.
 

SuperColey1

Guru Class Expert
Feb 17, 2007
503
1
16
49
Lincoln, UK
Well its been pretty cold here the last couple of weeks. Been snowing on the warmer days ;)

I have been basically adding equal warm to cold water as the cold coming from source is absolutely close to freezing.

I do have a combi boiler though so I guess the water isn't that warm for long nor a large amount either so maybe thats it.

AC
 

Dmaaaaax

Prolific Poster
Jan 9, 2009
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tinkerman;33935 said:
What is in the filter, any ammonia chips ect...? Thats a lot of salt to add at one time. If you had ammonia chips or some other stuff the salt would have released it as the recharging instructions. Just throwing out an idea.


No ammonia chips or activated carbon or purigen...etc, just filter floss and ceramics for biofiltration. I was doing ~1/4 of the recommonded dose of salt for a 75g tank and I tested for ammonia and nitrite, plus did multiple water changes. Definately not ammonia leeching back in.